1. family and parenting
2. motherhood
3. pregnancy

OBSTETRICS
Dr. P. Bernstein
Laura Loijens and Colleen McDermott, chapter editors
Tracy Chin, associate editor
NORMAL OBSTETRICS . . . . . . . . . . . . . . . . . . . . 2
Definitions
Diagnosis of Pregnancy
Investigations
Maternal Physiology
PRENATAL CARE . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Preconception Counseling
Initial Visit
Subsequent Visits
Gestation-Dependent Management
Prenatal Diagnosis
FETAL MONITORING. . . . . . . . . . . . . . . . . . . . . . 8
Antenatal Monitoring
Intra-Partum Monitoring
MULTIPLE GESTATION . . . . . . . . . . . . . . . . . . . .12
Background
Management
Twin-Twin Transfusion Syndrome
MEDICAL CONDITIONS IN PREGNANCY . . .13
Urinary Tract Infection (UTI)
Iron Deficiency Anemia
Folate Deficiency Anemia
Diabetes Mellitus (DM)
Gestational Diabetes Mellitus (GDM)
Hypertensive Disorders of Pregnancy
Hyperemesis Gravidarum
Isoimmunization
Infections During Pregnancy
ABNORMAL LABOUR . . . . . . . . . . . . . . . . . . . . . .34
Induction of Labour
Induction Methods
Augmentation of Labour
Abnormal Progress of Labour
Umbilical Cord Prolapse
Shoulder Dystocia
Breech Presentation
Vaginal Birth After Cesarean (VBAC)
Uterine Rupture
Amniotic Fluid Embolus
OPERATIVE OBSTETRICS . . . . . . . . . . . . . . . . . .39
Indications for Operative Vaginal Delivery
Forceps
Vacuum Extraction
Lacerations
Episiotomy
Cesarean Delivery
OBSTETRICAL ANESTHESIA . . . . . . . . . . . . . . .40
Pain Pathways During Labour
Analgesia
Anesthesia
NORMAL PUERPERIUM . . . . . . . . . . . . . . . . . . .42
Definition
Post-Delivery Examination
Breast
Uterus
Lochia
Postpartum Care
ANTENATAL HEMORRHAGE . . . . . . . . . . . . . . .22
First and Second Trimester Bleeding
Therapeutic Abortions
Third Trimester Bleeding
Placenta Previa
Abruptio Placentae
Vasa Previa
PUERPERAL COMPLICATIONS . . . . . . . . . . . . .42
Retained Placenta
Uterine Inversion
Postpartum Pyrexia
Postpartum Hemorrhage (PPH)
Postpartum Mood Alterations
GROWTH DISCREPANCIES . . . . . . . . . . . . . . . . .26
Intra-Uterine Growth Restriction (IUGR)
Macrosomia
Polyhydramnios
Oligohydramnios
DRUGS CONTRAINDICATED IN . . . . . . . . . . . .44
PREGNANCY
Antibiotics
Other Drugs
Immunizations
Breast Feeding and Drugs
ANTENATAL COMPLICATIONS . . . . . . . . . . . . .28
Preterm Labour
Rupture of Membranes
Chorioamnionitis
Post-Date Pregnancy
Intrauterine Fetal Death
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
NORMAL LABOUR AND DELIVERY . . . . . . . . .31
The Fetus
The Cervix
Definition of Labour
Four Stages of Labour
The Cardinal Movements of Fetus During Delivery
MCCQE 2002 Review Notes
Obstetrics – OB1
NORMAL OBSTETRICS
DEFINITIONS
Gravidity
❏ the total number of pregnancies of any gestation
• includes current pregnancy, abortions, ectopic pregnancies, and hydatidiform moles
• twins count as one pregnancy
Parity
❏ the number of pregnancies that have been carried to > 20 weeks
• twins count as one
• grand multiparity is parity of 4 or more
❏ four letter description (T P A L)
• T: number of term infants delivered (> 37 weeks)
• P: number of premature infants delivered (20 to 37 weeks)
• A: number of abortions (< 20 weeks)
• L: number of living children
Trimesters
❏ T1 (first trimester): 0 to 12 weeks
❏ T2 (second trimester): 12 to 28 weeks
❏ T3 (third trimester): 28 to 40 weeks
❏ normal pregnancy term: 37 to 42 weeks
Abortion
❏ loss of intrauterine pregnancy prior to viability of fetus
• < 20 weeks and/or < 500 g fetal weight
• includes induced (therapeutic) and spontaneous (miscarriage)
Stillbirth
❏ loss of intrauterine pregnancy after 20 weeks and/or > 500 g fetal weight
Stillbirth Rate
❏ the annual number of stillbirths per 1,000 total births
Perinatal Mortality Rate
❏ the annual number of stillbirths and early neonatal deaths
(in the first seven days of life) per 1,000 total births
❏ causes
• prematurity
• congenital anomalies
Neonatal Mortality Rate
❏ the annual number of deaths of liveborn infants within 28 days per 1,000 live births
Infant Mortality Rate
❏ the annual number of deaths of liveborn infants in the first year of life
per 1,000 live births (includes neonatal mortality)
Maternal Mortality Rate
❏ the annual number of deaths of women while pregnant or within 90
days of pregnancy per 100,000 live births
• direct: from obstetrical causes such as ectopic, pregnancy induced hypertension (PIH),
post partum hemorrhage (PPH), infection, pulmonary embolus (PE)
• indirect: from pre-existing illness or by accident
Birth Rate
❏ the annual number of live births per 1,000 population
Fertility Rate
❏ the annual number of live births per 1,000 women aged 15-44 years
DIAGNOSIS OF PREGNANCY
Symptoms
❏ amenorrhea
❏ nausea and/or vomiting
❏ breast tenderness
❏ urinary frequency
❏ fatigue
OB2 – Obstetrics
MCCQE 2002 Review Notes
NORMAL OBSTETRICS
. . . CONT.
Signs
❏ softening of the cervix (Goodell’s sign): 4-6 weeks
❏ bluish discoloration of the cervix and vagina due to engorgement of
pelvic vasculature (Chadwick’s sign): 6 weeks
❏ uterine enlargement
❏ softening of the isthmus (Hegar’s sign): 6-8 weeks
INVESTIGATIONS
❏ ßhCG
• positive in the serum at 9 days post-conception
• positive in the urine 28 days after LMP (last menstrual period)
❏ transvaginal U/S
• 5 weeks: gestational sac visible (ßhCG = 1,200-1,500 mIU/mL)
• 6 weeks: fetal pole seen
• 7-8 weeks: fetal heart tones visible
❏ transabdominal U/S
• 6-8 weeks: intrauterine pregnancy visible (ßhCG = 6,500 mIU/mL)
MATERNAL PHYSIOLOGY
General Principles
❏ progesterone induces relaxation of smooth muscle, among other effects
❏ physiologic changes are more pronounced in multiple gestations
Cardiovascular System (CVS)
❏ increased cardiac output, heart rate, and blood volume (hyperdynamic circulation)
❏ decreased blood pressure (especially diastolic, maximal in T2) due to
decreased peripheral vascular resistance (PVR)
❏ blood flow to the uterus, kidneys, breasts, and skin increases with gestational age
❏ enlarging uterus compresses inferior vena cava (IVC) and pelvic veins leading to risk of hypotension
(by decreasing venous return) as well as varicose veins,
hemorrhoids and leg edema (because of increased venous pressure)
Hematologic System
❏ apparent decrease in hemoglobin and hematocrit due to hemodilution
• plasma volume increases more than RBC mass
❏ increased risk of deep vein thrombus (DVT) and pulmonary embolus (PE) secondary to hypercoagulable state
• increase in factors I, VII, VIII, IX, X, XII
• decrease in factors XI, XIII and antithrombin III activity
• venous stasis from uterine compression of veins
❏ increased leukocyte count but impaired function
• 5,000 to 12,000/uL in pregnancy
• up to 25,000/uL in labour/postpartum
• often have improvement in autoimmune conditions
❏ gestational thrombocytopenia
• occurs in 8% of gestations, possibly due to accelerated platelet consumption
• mild thrombocytopenia (> 70,000/uL), asymptomatic, no history of prior thrombocytopenia
• platelet counts normalize within 2-12 weeks following delivery
Respiratory System
❏ increased oxygen consumption by 20%
❏ increased sensitivity to carbon dioxide (progesterone effect on respiratory centre)
results in hyperventilation and respiratory alkalosis compensated by
increased renal excretion of serum bicarbonate
❏ 50% increase in minute ventilation
❏ decreased total lung capacity (TLC), functional residual capacity (FRC) and residual volume (TV)
(elevated diaphragms)
❏ vital capacity (VC) unchanged
❏ increased tidal volume (TV) by 35-50%
❏ increased alveolar ventilation by 65%
Gastrointestinal (GI) System
❏ increased gastroesophageal reflux
• decreased sphincter tone
• delayed gastric emptying
• increased intraabdominal pressure
❏ increased stasis in gallbladder
❏ decreased GI motility and constipation
❏ upward displacement of appendix (appendicitis may have atypical presentation)
❏ hemorrhoids caused by constipation and elevated venous pressure
MCCQE 2002 Review Notes
Obstetrics – OB3
NORMAL OBSTETRICS
. . . CONT.
Genitourinary (GU) System
❏ increased glomerular filtration rate (GFR) by 50% (therefore decreased BUN and serum creatinine) but
no change in urine output because of increased tubular reabsorption
❏ glycosuria can be physiologic; with increase in GFR the threshold for
glucose reabsorption can be surpassed
❏ increased urinary frequency
❏ physiologic dilatation of ureters and renal pelvis (R > L) due to
progesterone-induced smooth muscle relaxation and uterine enlargement
❏ increased incidence of UTI and pyelonephritis (see Medical Conditions in Pregnancy section)
Endocrine System
❏ estrogen
• main estrogen is estradiol
• production involves an intricate pathway, requiring maternal, placental and fetal contributions
• sudden decline may indicate fetal compromise
❏ progesterone
• produced by corpus luteum during first 7 weeks, thereafter synthesized by the placenta
• maintains the endometrium
• absolutely necessary for continuation of pregnancy
❏ human chorionic gonadotropin (hCG)
• produced by placental trophoblastic cells
• peptide hormone composed of two subunits: alpha (common to all glycoproteins)
and beta (specific to hCG)
• has LH-like action: maintains the corpus luteum
• serum ßhCG positive 8-9 days after ovulation
• plasma levels double every 1-2 days, peak at 8-10 weeks and
then fall to a plateau until delivery
• rule of 10s
• 10 IU at time of missed menses
• 100,000 IU at 10 weeks (peak)
• 10,000 IU at term
• levels below expected by dates suggest an ectopic pregnancy, abortion, or wrong dates
• levels higher than expected suggest multiple gestation,
molar pregnancy, trisomy 21, or wrong dates
❏ thyroid
• moderate enlargement and increased basal metabolic rate
• increased total thyroxine and thyroxine binding globulin (TBG)
• free thyroxine index and TSH levels are normal
❏ adrenal
• maternal cortisol rises throughout pregnancy (total and free)
❏ prolactin
• produced by maternal pituitary in response to increasing estrogen in pregnancy
• stimulates lactation
❏ relaxin
• produced by the corpus luteum/ovary
• relaxes symphysis pubis and other pelvic joints
• helps soften and dilate the cervix
• inhibits uterine contraction
❏ calcium metabolism
• total maternal Ca2+ decreased due to decreased albumin
• free ionized (i.e. active) proportion remains the same due to increased
parathyroid hormone (PTH) which results in increased bone resorption and gut absorption
• bone turnover increased but no loss of bone density because estrogen
counteracts PTH by inhibiting resorption
Neurologic System
❏ increased incidence of carpal tunnel syndrome and Bell's palsy
Integumentary System
❏ pigmentation changes (fade after delivery)
• increased pigmentation of perineum and areola
• chloasma (pigmentation changes under eyes and on bridge of nose)
• linea nigra (midline abdominal pigmentation)
• spider angiomas
• palmar erythema
❏ striae gravidarum (fade but seldom disappear)
OB4 – Obstetrics
MCCQE 2002 Review Notes
PRENATAL CARE
PRECONCEPTION COUNSELING
❏ medication
❏
❏
❏
❏
• folic acid to prevent neural tube defects (NTDs) (0.4 to 1 mg daily in all women, 4 mg if past NTD);
start 12 wks preconception
• iron supplementation in 2nd and 3rd trimester
proper nutrition and physical fitness
genetic history and risk factors
viral screening
• HBsAg, rubella, +/– HIV
social history
• alcohol, smoking, drug use
• domestic violence (50% of domestic violence begins in pregnancy)
• impact on family and occupation (maternity/paternity leave)
INITIAL VISIT
❏ fill out antenatal forms 1 and 2
History
❏ determine gestational age (GA) by dates from the first day of the LMP (if regular periods and sure dates)
❏ if LMP unsure, get a dating ultrasound (best between weeks 8-12)
❏ determine estimated date of conception (EDC) using Nägele’s Rule
• first day of LMP + 7 days – 3 months
• e.g. LMP = 1 Apr. 2001, EDC = 8 Jan. 2002
• modify appropriately for longer or shorter cycles
❏ obtain obstetrical history of all previous pregnancies:
GTPAL/year/sex/weight/gestational age/mode of delivery/length of
labour/complications/uterine surgery (myomectomy, D&C’s, cone biopsies)
❏ obtain relevant medical, social, and family history
❏ prenatal classes
Physical
❏ complete physical exam
❏ baseline blood pressure (BP) (important for interpreting subsequent changes)
❏ baseline weight
❏ pelvic exam
Investigations
❏ bloodwork
• CBC, blood group and type, Rh antibodies
• rubella titre, VDRL, HBsAg routine; HIV serology should be offered to all
(if viral screen not already done preconception)
❏ urine
• R&M, C&S
• asymptomatic bacteriuria in 5% of pregnant women
• if untreated, 25-30% will get a UTI in pregnancy (increased risk of preterm labour)
❏ pelvic exam
• Pap smear (if none within 6 months), culture for GC and chlamydia
Counselling
❏ exercise
• exercise should be maintained at approximately the same level as
before pregnancy
• muscle strength and flexibility improve posture and muscle tone
and reduce common discomforts of pregnancy
• aggressive exercise (prolonged jogging and skiing) should be
avoided as the developing fetus can affect balance
❏ nutrition
• in general, a daily caloric increase of 300 kcal throughout pregnancy is recommended
• for women who do not consume an adequate diet, a daily
multivitamin should be continued in the second trimester; otherwise
routine multivitamin supplementation is not necessary (only one
vitamin per day is recommended to avoid excess vitamin A)
• iron is the only known nutrient for which requirements during pregnancy
cannot be met by diet alone (see Iron Deficiency Anemia section)
❏ work
• for women who work, rest periods are recommended to avoid the likelihood of fatigue
• stressful work during pregnancy is associated with a greater risk of
preterm delivery and poor fetal growth
• heavy forms of work should be discouraged
MCCQE 2002 Review Notes
Obstetrics – OB5
PRENATAL CARE
. . . CONT.
❏ travel
• in general, travel by car, plane, or train is not harmful during pregnancy
• however, stress related to travel may be associated with preterm labour
❏ sexual intercourse
• sexual intercourse may continue throughout pregnancy except in
patients at risk for abortion, preterm labour, or those with placenta previa
• breast stimulation may induce uterine activity and is discouraged in
high-risk patients near term
• labour may follow coitus due to the effect of prostaglandins in the seminal fluid
SUBSEQUENT VISITS
❏ for low-risk, uncomplicated pregnancy
• q monthly until 28 weeks
• q 2 weeks from 28 to 36 weeks
• q weekly from 36 weeks until delivery
With Every Visit
❏ estimate GA
❏ ask about fetal movements, bleeding, leaking, cramping
❏ urine dip for glucose and protein
❏ weight gain
• expect gain of roughly 1 lb/month in first half of pregnancy,
1 lb/week in second half of pregnancy
• average weight gain 25-35 lbs
(40% of weight gain is due to products of conception)
❏ BP
❏ symphysis-fundal height (SFH) measurement: SFH should be within 2 cm of
gestational age in weeks between 20 and 37 weeks, i.e. SFH = 20 cm @ 20 weeks
• 12 weeks: fundus at pubic symphysis
• 20 weeks: fundus at umbilicus
• 37 weeks: fundus at sternum
❏ differential diagnosis of uterus (SFH) incorrect size for dates (accurate dates essential)
• maternal: diabetes mellitus
• maternal-fetal: poly/oligo-hydramnios, multiple gestation
• fetal: abnormal karyotype, IUGR, fetal anomaly, abnormal lie
❏ examination of abdomen for lie, position and presentation (Leopold maneuvers) in T3
❏ fetal heart tones starting at ~ 12 weeks using doppler U/S
Table 1. Gestation-Dependent Management
Gestational Age (weeks)
Management Issues
10-12
CVS
U/S for nuchal translucency (if available)
15-16 or up to term
Amniocentesis
16
MSS (maternal serum screen)
16-18
U/S for dates and structural assessment
Quickening (fetal movement felt by mother)
26 -28
50 g oral glucose challenge test (OGCT)
28
Repeat CBC
Rhogam to Rh negative woman
36
Rh antibody screen if indicated
GBS screen
6 (postpartum)
Follow-up visit
• discuss contraception
• breast exam and pelvic exam, Pap smear
• depression/mental health
OB6 – Obstetrics
MCCQE 2002 Review Notes
PRENATAL CARE
. . . CONT.
Maternal Serum Screen (MSS or Triple Screen)
❏ offered to all mothers at 16 weeks
❏ provides a risk estimate of whether the fetus may be affected with Down Syndrome,
trisomy 18, or an open neural tube defect (oNTD)
❏ other chromosomal abnormalities not detected; therefore still offer
amniocentesis/chorionic villous sampling (CVS) to high risk women
❏ results are highly dependent on gestational age, so accurate dating is important
❏ to make accurate diagnosis, positive MSS should be followed up with
U/S and/or amniocentesis
❏ three markers: maternal serum alpha-feto protein (MSAFP), ßhCG,
unconjugated estrogen (uE3)
• Trisomy 21: low MSAFP, high ßhCG, low uE3
• Trisomy 18: low MSAFP, low ßhCG, low uE3
❏ differential diagnosis of high MSAFP
• wrong gestational age
• > 1 fetus (e.g. twins)
• fetal demise
• oNTD
• abdominal wall defects (e.g. omphalocele)
❏ differential diagnosis of low MSAFP
• gestational trophoblastic neoplasia (GTN)
• incorrect GA
• missed abortion
• chromosomal anomalies (e.g. Trisomy 18, 21)
❏ 80% of Down’s babies born to women under 35 years, so MSS is a valuable screening tool
• sensitivity for Down Syndrome detection: 60%
• sensitivity for oNTD: 80-90%
❏ MSS has a 9.5% false positive rate if maternal age >35; lower false
positive rate for oNTD and T18
Group B Streptococcus (GBS)
❏ not harmful to mother
• 15-40% vaginal carrier rate
❏ danger of vertical transmission (neonatal sepsis, meningitis or pneumonia);
treatment of maternal GBS at time of delivery decreases morbidity and
mortality for neonates
❏ guidelines controversial: screening with vaginal cultures often done at 34-36 weeks,
but this does not always reflect colonization status at delivery;
some physicians screen all while others treat empirically only
❏ indications for antibiotic prophylaxis:
• positive GBS screen OR
• GBS status unknown and one of the following risk factors
• previous GBS bacteriuria even if treated
• previous infant with GBS infection
• preterm labour
• premature rupture of membranes (PROM) > 12 hours
• intrapartum maternal temperature > 37.7ºC
• fetal tachycardia
❏ treat with ampicillin 2 g IV load, then 1 g IV q4h until delivery
(if pen-allergic, use clindamycin)
PRENATAL DIAGNOSIS
Indications
❏ maternal age > 35 (increased risk of chromosomal anomalies)
❏ risk factors in current pregnancy
• teratogenic exposure
• abnormal MSS or U/S
❏ past history/family history of
• previous pregnancy with chromosomal anomaly or genetic disease
• either parent a known carrier of a genetic disorder or balanced translocation
• family history of chromosomal anomaly, genetic disorder,
birth defect, or undiagnosed mental retardation
• consanguinity
• three or more spontaneous abortions
MCCQE 2002 Review Notes
Obstetrics – OB7
PRENATAL CARE
. . . CONT.
Amniocentesis
❏ U/S-guided transabdominal extraction of amniotic fluid
❏ indications
• identification of genetic problems such as trisomies (15-16 weeks gestation)
• assessment of fetal lung maturity (third trimester)
• L/S ratio (lecithin:sphingomyelin): if > 2:1, fetal lungs are mature
enough that respiratory distress syndrome (RDS) is less likely to occur
• assessment of amniotic fluid bilirubin concentration in Rh-isoimmunized pregnancies
❏ advantages
• also screens for oNTD (acetylcholinesterase and amniotic AFP)
• more accurate genetic testing
❏ disadvantages
• 0.5% risk of spontaneous abortion
• results take 10-14 days; FISH available in 72 hours
❏ in women over 35 years, the risk of chromosomal anomaly (1/180) is greater than
the increased risk of miscarriage from the procedure, so it is offered routinely
Chorionic Villus Sampling (CVS)
❏ needle through abdomen or catheter through cervix at 10-12 weeks for CVS
❏ the chorion is of fetal origin and cells obtained by villus biopsy can be
examined using the same techniques as for amniocytes
❏ advantages
• enables pregnancy to be terminated earlier
• more rapid karyotyping, DNA tests, chromosome status,
biochemical assay (results in 48 hours; do not have to wait for culture)
• increasing availability of probes to allow diagnosis of genetic abnormalities (i.e. FISH)
• high sensitivity and specificity
❏ disadvantages
• 1-2% risk of spontaneous abortion
• does not screen for neural tube defects (NTD)
• risk of limb injury
• 1-2% incidence of genetic mosaicism ––> false negative results
Table 2. Amniocentesis versus CVS
Amniocentesis
CVS
Accuracy of prenatal cytogenetic diagnosis
99.8%
97.5%
Detection of cytogenetic abnormality
3.4%
5.6%
Laboratory failure
0.1%
2.3%
FETAL MONITORING
ANTENATAL MONITORING
Fetal Movements
❏ assessed by
• maternal perception (quickening)
• choose a time when baby is normally active to count movements
• if < 6 movements in 2 hours, notify MD
• 10 movements in 12 hour period is lower limit of normal (32 weeks and over)
• false positive rate = 30-60%, false negative rate is < 5%
• palpation
• U/S
Ultrasound
❏ routinely done at 16-20 weeks to assess fetal growth and anatomy
❏ earlier or subsequent U/S only when medically indicated
• confirmation of intrauterine pregnancy
• identification of multiple pregnancy
• past history of early fetal losses
• bleeding or other complications
• measurement of fetal growth and identifiation of IUGR
• placental localization
• determining gestational age (most accurately determined through
measurement of crown-rump length prior to 11-12 weeks gestational age)
• assessment of amniotic fluid index (AFI): total of largest amniotic fluid pocket
measurements in 4 quadrants of gestational sac, normally 8-24 cm
OB8 – Obstetrics
MCCQE 2002 Review Notes
FETAL MONITORING
. . . CONT.
Non-Stress Test (NST)
❏ constant fetal heart rate (FHR) tracing using an external doppler to assess FHR and its relationship to
fetal movement (see Intrapartum Fetal Cardiotocography section)
❏ indicated when there is any suggestion of uteroplacental insufficiency or suspected fetal distress
❏ false positive rate depends on duration; false negative rate = 0.2-0.3%
❏ reactive NST (normal/negative result)
• at least 2 accelerations of FHR > 15 bpm from the
baseline lasting ≥ 15 seconds, in 20 minutes
❏ nonreactive NST (abnormal/positive result)
• < 2 FHR accelerations > 15 bpm and 15 seconds
duration associated with fetal movement in 40 minutes
• if no observed accelerations or fetal movement in the first
20 minutes, stimulate fetus (fundal pressure, acoustic/vibratory
stimulation) and continue monitoring for 30 minutes
• if NST nonreactive, then perform biophysical profile (BPP)
Biophysical Profile (BPP)
❏ consists of NST and 30 minute U/S assessment of the fetus
❏ five scored parameters of BPP (see Table 3)
❏ scores
• 8-10: perinatal mortality rate 1:1,000; repeat BPP as clinically indicated
• 6: perinatal mortality 31:1,000; repeat BPP in 24 hours
• 0-4: perinatal mortality rate 200:1,000; deliver fetus if mature
❏ amniotic fluid volume (AFV) = a marker of chronic hypoxia, all other parameters indicate acute hypoxia
❏ false positive rate = < 30%, false negative rate = 0.1%
Table 3. Scoring of the Biophysical Profile
Parameter
Reassuring (2)
Non-Reassuring (0)
AFV
Fluid pocket of 2 cm in 2 axes
Oligohydramnios
NST
Reactive
Nonreactive
Breathing
At least one episode of breathing
lasting at least 30 seconds
No breathing
Limb Movement
Three discrete movements
Two or less
Fetal Tone
At least one episode of limb
extension followed by flexion
No movement
INTRA-PARTUM MONITORING
Vaginal Exam
❏ membrane status
❏ cervical effacement (thinning), dilatation, consistency, position, application
• a - application
• b - position
• c - consistency
• d - dilatation
• e - effacement
❏ fetal presenting part, position, and station
❏ bony pelvis size and shape
Intrapartum Fetal Cardiotocography (CTG)
❏ intermittent auscultation or continuous electronic monitoring are
acceptable methods of intrapartum surveillance in both low and high-risk
pregnancies (longer checking intervals in uncomplicated pregnancies)
❏ no scientific evidence has identified the most effective method of fetal surveillance
(including frequency and duration) that ensures optimum results
❏ continuous electronic monitoring: external (doppler) vs. internal (scalp electrode) monitoring
❏ internal monitoring recommended after abnormal fetal heart rate (FHR) found on external monitoring
❏ described in terms of baseline FHR, variability (short term, long term) and periodicity
(accelerations, decelerations)
❏ baseline FHR
• normal range is 120-160 bpm
• a parameter of fetal well-being vs. distress
MCCQE 2002 Review Notes
Obstetrics – OB9
FETAL MONITORING
. . . CONT.
❏ variability: an indicator of fetal oxygenation
• short term: beat to beat (requires scalp monitor)
• long term: described with respect to frequency and amplitude of change in baseline
• frequency: number of times in a 1 minute period of an increase or
decrease of at least 5 bpm lasting 5 seconds (average frequency is 3)
• amplitude: difference between highest and lowest
FHR within a 1 minute period (11-25 bpm is average)
❏ periodicity
• accelerations
• increase of ≥ 15 bpm lasting ≥ 15 seconds,
in response to fetal movement or uterine contraction
• decelerations
• 3 types, described in terms of shape, onset, depth, duration, recovery,
occurrence, and impact on baseline FHR and variability
• early decelerations (see Figure 1)
• uniform shape with onset early in contraction;
returns to baseline by end of contraction
• slow gradual deceleration
• often repetitive; no effect on baseline FHR or variability
• due to vagal response to head compression
• benign, usually seen with cervical dilatation of 4-7 cm
BPM
180
160
140
120
100
onset of deceleration
nadir of
deceleration
acme of
contraction
onset of
contraction
FHR (baseline)
Uterine Contraction (baseline)
end of
contraction
Figure 1. Early Decelerations
• variable decelerations (see Figure 2)
• variable in shape, onset, and duration
• most common type of periodicity seen during labour
• may or may not be repetitive
• often with abrupt rapid drop in FHR; usually no effect on
baseline FHR or variability
• due to cord compression or, in second stage,
forceful pushing with contractions
• benign unless repetitive, with slow recovery, or when
associated with other abnormalities of FHR
• rule of 60s for severe variable decelerations: decels to
< 60 bpm, or > 60 bpm below baseline and > 60 s in
duration with slow return to baseline
BPM
160
140
120
FHR
variable in duration,
intensity, and timing
100
Uterine Contraction
Figure 2. Variable Decelerations
• late decelerations (see Figure 3)
• uniform shape with onset late in contraction, lowest depth after peak
of contraction, and return to baseline after end of contraction
• may cause decreased variability and change in baseline FHR
• must see 3 in a row, all with the same shape to define a late deceleration
• due to fetal hypoxia and acidemia, maternal hypotension or uterine hypertonus
• usually a sign of uteroplacental insufficiency (ominous)
• manage with position change to left lateral decubitus, oxygen, stop oxytocin,
correct maternal hypertension, fetal scalp pH, +/– C/S when necessary
OB10 – Obstetrics
MCCQE 2002 Review Notes
FETAL MONITORING
. . . CONT.
BPM
onset of deceleration
160
nadir of
FHR
140
deceleration
120
recovery time
100 30 seconds of
lag time
acme of
contraction
onset of
contraction
Uterine Contraction
end of
contraction
Figure 3. Late Decelerations
Table 4. Factors Affecting Fetal Heart Rate
Fetal Tachycardia
(FHR >160)
Fetal Bradycardia
(FHR <120)
Decreased Variability
Maternal Factors
Fever
Hyperthyroidism
Anemia
Hypothermia
Hypotension
Hypoglycemia
Infection
Dehydration
Fetal Factors
Arrhythmia
Anemia
Rapid descent
Dysrhythmia
Heart block
CNS anomalies
Dysrhythmia
Inactivity/sleep cycle
Drugs
Sympathomimetics (ritodrine)
Beta blockers
Anesthetics
Narcotics
Magnesium sulphate
Uteroplacental
Early hypoxia (abruption, PIH)
Chorioamnionitis
Late hypoxia (abruption, PIH)
Acute cord prolapse
Hypercontractility
Hypoxia
Approach to Abnormal FHR
❏ if external monitor, ensure fetal tracing and not maternal
❏ change position of mother
❏ give 100% oxygen by mask and discontinue oxytocin
❏ rule out cord prolapse
❏ consider fetal scalp electrode to assess beat-to-beat variability and
fetal scalp blood sampling if abnormality persists
❏ immediate delivery if recurrent prolonged bradycardia
Fetal Scalp Blood Sampling
❏ indicated when fetal distress is suggested by clinical parameters including
heavy meconium or moderate to severely abnormal FHR patterns
❏ > 7.25 is normal
❏ < 7.25 indicates that test should be repeated in 30 minutes
❏ < 7.20 indicates fetal acidosis severe enough to warrant immediate delivery
Meconium in the Amniotic Fluid
❏ usually not present early in labour
❏ classified as: early (prior to ROM) or late (after rupture of membranes (ROM) with clear fluid)
❏ can be thick or thin
• thin meconium: light green or yellow, not usually associated with poor outcome
• thick meconium: dark green or black, pea-soup consistency,
associated with lower APGARs and increased risk of meconium aspiration
• call pediatrics to delivery
• may indicate undiagnosed breech
❏ increasing meconium during labour may be a sign of fetal distress
❏ in general, meconium may be present in up to 25% of all labours;
usually NOT associated with poor outcome, but extra care is required
at time of delivery to avoid aspiration
MCCQE 2002 Review Notes
Obstetrics – OB11
MULTIPLE GESTATION
BACKGROUND
❏ incidence of twins is 1/80 and triplets 1/6400 in North America
❏ 2/3 of twins are dizygotic (i.e. fraternal)
❏ hereditary factors (on maternal side only) and fertility drugs/procedures
affect the dizygotic twins rate only
❏ monozygous twinning occurs at a constant rate worldwide (1/250)
❏ determination of zygosity by number of placentas, thickness of membranes, sex, blood type
A
Monoamnionic
D
Diamnionic
Monochorionic
(forked Cord)
Dichorionic
(fused)
*0-72 hrs
(see Colour Atlas OB3)
B
Monoamnionic
E
Diamnionic
Monochorionic
*9-12 d
Dichorionic
(separated)
C
Diamnionic
F
Monoamnionic
Monochorionic
*4-8 d
(see Colour Atlas OB4)
Monochorionic
(Double Monster, one cord)
Figure 4. Classification of Twin Pregnancies
*Indicates time of cleavage
Illustration by David Hou
Table 5. Complications Associated with Multiple Gestation
Maternal
Utero-placental
Fetal
Hyperemesis gravidarum
GDM
Preeclampsia/PIH
Anemia (increased iron and folate needs)
Increased physiological stress on all systems
Increased compressive symptoms
C/S
Increased PROM/PTL
Polyhydramnios
Placenta previa
Placental abruption
PPH (uterine atony)
Umbilical cord prolapse
Cord anomalies
(velamentous insertion,
2 vessel cord)
Prematurity*
IUGR
Malpresentation
Congenital anomalies
Twin-twin transfusion (DA/MC)
Increased perinatal morbidity and mortality
Twin interlocking (twin A breech, twin B vertex)
Single fetal demise (may lead to DIC)
*Most common cause of perinatal mortality in multiple gestation
PIH = pregnancy induced hypertension
PPH = postpartum hemorrhage
GDM = gestational diabetes mellitus
OB12 – Obstetrics
DIC = disseminated intravascular coagulation
DA = diamnionic
MC = monochorionic
MCCQE 2002 Review Notes
MULTIPLE GESTATION
. . . CONT.
MANAGEMENT
❏ rest in T3 (increases uterine blood flow)
❏ increased antenatal surveillance
• nonstress test (NST) q weekly from 24 weeks GA
• serial U/S q 2-3 weeks from 28 weeks GA to assess growth
• doppler flow studies q weekly if discordant fetal growth
• BPP as needed
❏ vaginal examinations in third trimester to check for cervical dilatation
❏ may attempt vaginal delivery if twin A presents as vertex, otherwise C/S
(40-50% of all twin deliveries, 15% of cases have twin A delivered vaginally
and twin B delivered by C/S)
❏ mode of delivery depends on fetal weight, GA, presentation
TWIN-TWIN TRANSFUSION SYNDROME
❏
❏
❏
❏
10% of monochorionic twins
arterial blood from donor twin passes through placenta into vein of recipient twin
donor twin: IUGR, hypovolemia, hypotension, anemia, oligohydramnios
recipient twin: hypervolemia, hypertension, CHF, polycythemia, edema,
polyhydramnios, kernicterus in neonatal period
❏ management: therapeutic serial amniocentesis to decompress
polyhydramnios of recipient twin and decrease pressure in
cavity and on placenta; laser occlusion of placental vessels
MEDICAL CONDITIONS IN PREGANCY
URINARY TRACT INFECTION (UTI)
❏ most common medical complication of pregnancy
❏ asymptomatic bacteriuria in 2-7% of pregnant women depending on parity
and socioeconomic factors
Pathophysiology
❏ due to increased urinary stasis from mechanical and hormonal (progesterone) factors
❏ organisms are the same as non-pregnant woman, and also GBS
Signs and Symptoms
❏ range from minimal to severe
❏ if urethra infected there will be some degree of dysuria, urgency, and frequency
Investigations
❏ urinalysis, urine culture
❏ VCUG, cystoscopy, and renal function tests in recurrent infections
Management
❏ uncomplicated UTI
• first line: amoxicillin
• alternatives: TMP-SMX (Septra) or nitrofurantoin (avoid sulpha drugs during
last 6 weeks of pregnancy due to displacement of bilirubin from albumin
and increased kernicterus in the newborn)
• follow with monthly urine cultures
• recurrence common
❏ pyelonephritis
• hospitalization and IV antibiotics
Complications
❏ acute cystitis, pyelonephritis, and possible PPROM
RED FLAGS
❏ may be asymptomatic; treat ALL pregnant women with bacteriuria to prevent preterm labour
IRON DEFICIENCY ANEMIA
❏ iron requirements increase during pregnancy due to
• fetal/placental growth (500 mg)
• increased maternal RBC mass (500 mg)
• losses (200 mg)
❏ mother needs 1,000 mg of elemental iron per fetus; this amount exceeds normal stores + dietary intake
❏ responsible for 80% of causes of nonphysiologic anemia during pregnancy
MCCQE 2002 Review Notes
Obstetrics – OB13
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Etiology
❏ inadequate iron intake
❏ decreased iron absorption (malabsorption syndrome, antacid use)
❏ increased losses (bleeding from vaginal or other source)
❏ increased requirement (fetal growth, multiple gestation)
Signs and Symptoms
❏ non-specific symptoms: pallor, fatigability, palpitations, tachycardia, and dyspnea
❏ severe anemia: angular stomatitis, glossitis, and koilonychia
Investigations
❏ serum iron, serum ferritin, blood smear
(total iron binding capacity (TIBC) not reliable because of increase during pregnancy)
Management
❏ prevention: 150 mg ferrous sulfate OD, 300 mg ferrous gluconate OD,
or 30 mg of ferrous iron OD for all pregnant women in 2nd and 3rd trimester
❏ if anemic: 1 g ferrous sulfate OD (180 mg elemental Fe)
Complications
❏ maternal: angina, CHF, infection, slower recuperation, preterm labour
❏ fetal: decreased oxygen carrying capacity leading to fetal distress,
IUGR, low birth weight and hydrops
FOLATE DEFICIENCY ANEMIA
❏
❏
❏
❏
❏
❏
most often associated with iron deficiency anemia
incidence varies from 0.5-25% depending on region, population, diet
necessary for closure of neural tube during early fetal development
minimum daily requirement is 0.4 mg
takes approximately 18 weeks of folate deficient diet to produce anemia
non-nutritional factors include: multiple gestation, drugs (phenytoin, methotrexate),
chronic hemolytic anemia, malabsorption entities (sprue)
Signs and Symptoms
❏ non-specific symptoms: anorexia, nausea, vomiting, diarrhea, depression,
pallor, UTI, sore mouth or tongue
Investigations
❏ serum folate, blood smear
Prevention
❏ 0.4 to 1 mg folic acid PO daily for 1-3 months preconceptually and throughout T1
❏ 4 mg folic acid per day with past history of NTD
Complications
❏ maternal: smaller blood volume, nausea, vomiting, anorexia
❏ fetal: NTD in T1, low birth weight, prematurity
DIABETES MELLITUS (DM)
Incidence
❏ 2-3% of pregnancies are complicated by diabetes mellitus
Normal Physiology in Pregnancy
❏ in early pregnancy (T1) insulin secretion is increased and its anabolic
actions are potentiated, decreasing fasting maternal glucose levels and
promoting maternal energy storage
❏ in later pregnancy (T2, T3) insulin resistance develops
❏ anti-insulin factors: human placental lactogen (increased secretion with growth of the placenta)
and cortisol
❏ result: higher fasting glucose and enhanced lipolysis (increased FFA, TG, lipids, ketones)
to supply energy for fetal growth
Classification of Diabetes Mellitus
❏ Insulin Dependent DM (Type 1)
❏ Non-Insulin Dependent DM (Type 2)
❏ Gestational Diabetes (GDM): DM occurring in pregnancy
OB14 – Obstetrics
MCCQE 2002 Review Notes
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Complications of Pregnancy in the Diabetic
❏ maternal
• hypertension/PET, polyhydramnios, pyelonephritis/UTI
• ketoacidosis, diabetic coma, worsening retinopathy and
nephropathy in Type 1 or Type 2, NOT in GDM
❏ fetal
• macrosomia: maternal hyperglycemia leads to fetal hyperinsulinism
resulting in accelerated anabolism and macrosomia
• congenital anomalies: cardiac (VSD), NTD, GU (cystic kidneys),
GI (anal atresia), MSK (sacral agenesis)
• IUGR
• delayed fetal lung maturity (hyperglycemia interferes with surfactant synthesis)
• preterm labour/prematurity
• increased incidence of spontaneous abortion
• increased incidence of stillbirth
• note: pregnancies complicated by GDM do not manifest an increased
risk of congenital anomalies because it develops later (i.e. after T1)
❏ neonatal
• macrosomia and associated birth trauma, hypoglycemia, hyperbilirubinemia
and jaundice, hypocalcemia, polycythemia, and RDS
Management of Type 1 and Type 2 DM in Pregnancy
❏ before pregnancy
• optimize glycemic control
• counsel patient re: potential risks and complications
• advise preconception folic acid
• evaluate for diabetic retinopathy, neuropathy, coronary artery disease
• refer to diabetes clinic
❏ during pregnancy
• measure HbA1C (indicates glycemic control during
embryogenesis and can be used to estimate risk of birth defects)
• switch type 2 diabetics to insulin (oral hypoglycemics contraindicated)
• monitor as for normal pregnancy plus
• initial 24-hr urine protein and creatinine clearance, retinal exam, HbA1C
• encourage increased blood sugar self-monitoring
• periodic HbA1C and urine C&S
• increased fetal surveillance (BPP, NST)
• < 36 weeks: q 1-2 weeks
• > 36 weeks: q weekly or biweekly
• consider fetal echo for congenital heart disease
• admit for blood sugar control as needed
• note: in T2 the demand for insulin is increased; adjust dosages
• MSAFP may be decreased in diabetic pregnancies,
altering interpretation of this test
❏ during labour
• timing of delivery depends on fetal and maternal risk factors
• can wait for spontaneous labour if glucose well-controlled and BPP normal
• induce by 40 weeks
• increased risk of CPD and shoulder dystocia with babies > 4,000 g (8.8 lbs)
• elective C/S for predicted birthweights > 4,500 g (9.9 lbs) (controversial)
• during labour monitor sugars q1h with patient on insulin and dextrose drip;
aim for blood sugar of 3.5 to 6.5 to reduce the risk of neonatal hypoglycemia
❏ postpartum
• insulin requirements dramatically drop with expulsion of placenta
which produced insulin antagonists
• no insulin is required for 48-72 hours post-partum in most type 1 diabetes
• monitor glucose q6h, restart insulin at two-thirds pre-pregnancy dosage
when glucose > 8 mmol/L
GESTATIONAL DIABETES MELLITUS (GDM)
❏ glucose intolerance that is present only during pregnancy
❏ 50% risk of developing Type 2 DM in next 20 years
❏ varies from 12% in racially heterogenous urban regions to 1% in rural areas
with a predominantly white population
MCCQE 2002 Review Notes
Obstetrics – OB15
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Risk Factors
❏ maternal: age > 25, obesity, excess weight gain in pregnancy, early PIH
or polyhydramnios, repeated vaginal candidiasis, high risk ethnic groups
❏ past history: previous GDM, congenital anomaly, unexplained stillbirth,
macrosomic infant (> 4.5 kg)
❏ family history: GDM, Type 2 DM, macrosomic infant
❏ fetal: wt > 4,500 g or large gestational age (LGA), multiple gestation
Diagnosis
❏ screen all women between 24-28 weeks with 50 g oral glucose challenge test (OGCT)
❏ > 7.8 mmol/L (140 mg/dL) at 1 hour is abnormal
❏ ≥ 10.3 mmol/L (200 mg/dL) at 1 hour is diagnostic of GDM
❏ if OGCT result is 7.8-10.3, follow-up with 2 hour 75 g oral glucose tolerance test (OGTT)
• GDM diagnosis with 2 or more of: blood glucose before test ≥ 5.3,
blood glucose at 1 hour ≥ 10.6 or 2 hour blood glucose ≥ 8.9
Management
❏ aim to achieve normal blood sugars post-prandially
❏ start with diabetic diet (note: weight-reducing diets not recommended due to risk of ketonemia)
❏ if blood sugars not well-controlled with diet alone, may need to add insulin
❏ oral hypoglycemic agents contraindicated in pregnancy
❏ fetal monitoring and timing of delivery same as for DM above
❏ insulin and diabetic diet should be stopped post-partum but
encourage regular exercise and attainment of healthy body weight as
there is increased risk of overt DM
❏ follow-up testing recommended (i.e. OGTT at 6 weeks and 6 months postpartum)
Complications
❏ maternal: polyhydramnios, pre-eclampsia, diabetic emergencies
❏ fetal: macrosomia with traumatic delivery, delayed organ maturity,
congenital anomalies, IUGR
HYPERTENSIVE DISORDERS OF PREGNANCY
Classification
❏ A: preeclampsia/eclampsia/pregnancy-induced hypertension (incidence = 6%)
❏ B: chronic hypertension (incidence = 2.5%)
❏ C: chronic hypertension with superimposed preeclampsia/eclampsia
❏ D: transient hypertension
A. PREGNANCY-INDUCED HYPERTENSION/
PREECLAMPSIA/TOXEMIA/ECLAMPSIA (PIH)
❏ hypertension accompanied by proteinuria and/or non-dependent
edema with onset > 20 weeks
• systolic BP > 140 mmHg or at least 30 mmHg above
non-pregnant/T1 sBP
• diastolic BP > 90 mmHg or at least 15 mmHg above non-pregnant/T1 dBP
• proteinuria is defined as > 1+ protein on random dipstick analysis
or > 300 mg in a 24 hour urine collection
• non-dependent edema (e.g. face, hands) that is generalized and usually associated
with excessive weight gain (> 2 kg/week); this criterion is clinically useful
but no longer strictly part of the PIH definition
❏ 50% of all hypertension in pregnancy
❏ due to an imbalance of thromboxane (vasoconstrictor) and
prostaglandin (vasodilator), causing generalized arteriolar constriction
––> capillary damage ––> protein extravasation and hemorrhage
❏ caution: patients with GTN (mole or choriocarcinoma) may present
with classic features of PIH in T1 or T2
Classification
❏ mild PIH: uncomplicated by neurologic symptoms or criteria for a diagnosis of severe PIH
OB16 – Obstetrics
MCCQE 2002 Review Notes
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Severe PIH
❏ severe PIH: complicated by at least two of the following
• BP > 160/110
• respiratory: pulmonary edema or cyanosis
• cardiac: congestive heart failure
• renal: proteinuria > 5 g/24 hours or > 2+ on dipstick, elevated serum creatinine,
oliguria (< 400 mL/24 hours)
• hepatic: elevated liver enzymes, right upper quadrant (RUQ) or epigastric pain
(subcapsular hemorrhage), ascites, hyperbilirubinemia, HELLP
• neurologic: visual disturvances (i.e. scotomas, loss or peripheral vision), hyperreflexia,
clonus, headache (cerebral artery vasospasm), convulsions (eclampsia)
• gastrointestinal: severe nausea/vomiting
• hematologic: thrombocytopenia, microangiopathic hemolysis
• fetal: IUGR
❏ eclampsia: grand mal seizures in a woman with preeclampsia
Risk Factors for Development of PIH
❏ maternal factors
• 80-90% of cases in primagravidas
• past history or family history of PIH
• diabetes, chronic hypertension, or renal disease
• antiphospholipid antibody syndrome
• extremes of maternal age
❏ fetal factors
• IUGR
• hydatidiform mole
• > 1 fetus
• fetal hydrops
Prophylaxis (For Those with Risk Factors)
❏ calcium supplementation, aspirin, and fish oil supplementation have all been
investigated as prophylactic treatments of PIH; results vary and are uncertain
Management of Mild PIH
❏ maternal evaluation
• history and physical examination (see above criteria)
• laboratory
• CBC and electrolytes
• renal function tests: BUN, creatinine, uric acid
• liver enzymes and coagulation studies: PT, PTT, FDP, d-dimers
• urinalysis for protein and casts
• 24 hour urine for protein and creatinine clearance
❏ fetal evaluation of FHR, NST, BPP, doppler flow
❏ management with bed rest in left lateral decubitus position (reduces abdominal vessel compression)
❏ normal dietary salt and protein intake
❏ no use of diuretics/antihypertensives
Management of Severe PIH
❏ stabilize and deliver; the only "cure" is delivery
❏ vaginal induction of delivery is preferred unless patient or fetus is seriously ill, then C/S
❏ admit and complete maternal evaluation (same as for mild)
• keep NPO
• start IV, cross and type
• foley catheter to monitor urine output
❏ maternal monitoring
• hourly input and output, check urine q12 hours for protein
• vitals and DTR q1 hour
❏ fetal evaluation
• NST followed by continuous electronic fetal monitoring until delivery; doppler flow
❏ anticonvulsant therapy
• given to increase seizure threshold
• baseline magnesium blood level
• magnesium sulfate (4 g IV bolus over 20 min) followed by maintenance of 2-4 g/hour
• excretion of magnesium sulfate is via kidney therefore
patients with oliguria require a lower infusion rate
• signs of magnesium toxicity: depressed deep tendon reflexes (DTR), RR < 10/minute,
urine output < 25 cc/hr, decreased muscle tone, CNS or cardiac depression
• antagonist to magnesium sulfate is calcium gluconate (10%) 10 mL (1 g) IV over 2 minutes;
may require mechanical ventilation if respiratory arrest occurs
MCCQE 2002 Review Notes
Obstetrics – OB17
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
❏ antihypertensive therapy
• decreasing the BP decreases the risk of stroke (indicated only if BP > 140-170/90-110)
• first line: hydralazine 5-10 mg IV bolus over 5 minutes q15-30 minutes until desired effect
(an arteriolar vasodilator with minimal venous effect; short-term only)
• second line: labetalol 20-50 mg IV q10 minutes
• third line: nifedipine (Adalat) 10-20 mg po q20-60 minutes
• ACE-inhibitors should be avoided
❏ postpartum management
• all antepartum therapy and monitoring continued until stable
• risk of seizure highest in first 24 hours postpartum
• continue magnesium sulfate for 12-24 hours after delivery
• the patient who continues to remain in serious condition may have HELLP
• most women return to a normotensive BP within 2 weeks but BP may worsen transiently in that time
Management of Eclampsia
❏ airway, breathing, circulation
❏ seizure control and prevention (see Neurology Chapter)
• do not attempt to shorten or abolish the initial convulsion
• prevent maternal injury and maintain adequate oxygenation
• minimize risk of aspiration, auscultate lungs after every seizure
• give adequate magnesium sulphate as soon as convulsion has ended
• correct maternal acidemia (obtain post-ictal blood gases)
• some use valium for seizure control
Maternal Complications of PIH
cerebral hemorrhage (50% of deaths)
left ventricular failure/pulmonary edema
liver and renal dysfunction
abruption
seizures
DIC: release of placental thromboplastin, leading to a consumptive coagulopathy
HELLP
• hemolysis, elevated liver enzymes, low platelets
• may only respond to fresh frozen plasma with plasma exchange
❏
❏
❏
❏
❏
❏
❏
Fetal Complications of PIH
❏ mainly due to placental insufficiency
• fetal loss
• IUGR
• prematurity
• abruptio placentae
B. CHRONIC HYPERTENSION
❏ definition
• history of hypertension (> 140/90) before gestation or prior to 20 weeks gestation
(unless there is a GTN)
• persistence of hypertension postpartum
• strong family history of hypertension
• most gravidas have essential hypertension, associated with an increased risk of
preeclampsia or eclampsia, abruptio placenta, IUGR and IUD
❏ management
• methyldopa and/or labetalol and/or atenolol
• no ACE inhibitors, diuretics, propranolol (risk of teratogenic effects)
• monitor fetus with serial U/S
C. CHRONIC HYPERTENSION WITH SUPERIMPOSED PIH
❏ 2-7 fold increased likelihood of developing preeclampsia/eclampsia
if pre-existing maternal hypertension
❏ tends to recur
❏ occurs early in pregnancy, tends to be severe, often with IUGR
D. TRANSIENT HYPERTENSION
❏
❏
❏
❏
occurs in the second half of pregnancy, during labour, or 48 hours after delivery
no significant proteinuria (< 300 mg/24 hours)
extremely difficult to differentiate from preeclampsia (retrospective diagnosis)
often predictive of later development of essential hypertension
OB18 – Obstetrics
MCCQE 2002 Review Notes
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
HYPEREMESIS GRAVIDARUM
Definition
❏ intractable nausea and vomiting, causing weight loss, dehydration, ketonuria,
electrolyte imbalance, acid-base disturbance and if severe, hepatic and renal damage
❏ usually present in T1 then diminishes; persists throughout pregnancy in a minority
Etiology
❏ presently thought to be multifactorial with hormonal, immunologic and psychologic components
❏ high or rapidly rising ßhCG or estrogen levels are implicated
Differential Diagnosis of Nausea and Vomiting
❏ hyperemesis is a diagnosis of exclusion
❏ GI inflammation/infection
• appendicitis
• cholecystitis
• hepatitis
• gastroenteritis
• pancreatitis
• peptic ulcer disease (PUD)
• fatty liver of pregnancy
❏ pyelonephritis
❏ thyrotoxicosis
❏ multiple gestation
❏ gestational trophoblastic neoplasia (GTN) (see Gynecology Chapter)
❏ HELLP syndrome
Investigations
❏ labs (CBC, lytes, BUN and creatinine, urinalysis, LFTs)
❏ ultrasound (to R/O molar pregnancy, multiple pregnancy and to assess
liver, pancreas, gallbladder, etc.)
Management
❏ general
• early recognition is important
• if severe, admit to hospital
• NPO initially, then small frequent meals of appealing foods
• correct hypovolemia, electrolyte imbalance and ketosis
• thiamine, if indicated
• TPN if severe to reverse catabolic state
• consider emotional support, dietary and psychologic counselling
❏ pharmacological options
• Diclectin (vitamin B6 and doxylamine succinate)
❏ non-pharmacological options
• accupressure at inner aspect of the wrists, just proximal to the flexor crease
has been shown to significantly reduce symptoms of nausea and vomiting
• avoid triggers (i.e. certain smells)
• rest
Maternal Complications
❏ Mallory Weiss tears
❏ Wernicke's encephalopathy, if protracted course
❏ death
Fetal Complications
❏ usually none
❏ IUGR is 15x more common in women losing > 5% of prepregnant weight
ISOIMMUNIZATION
Etiology
❏ antibodies produced against a specific RBC antigen as a result of
antigenic stimulation with RBC of another individual
❏ most common is anti-Rh Ab produced by a sensitized Rh-negative mother
(more than 90% of cases of Rh isoimmunization are due to D antigens)
❏ other antibodies can lead to fetal red blood cell hemolysis
• much less common and no prophylaxis is available
❏ overall risk of isoimmunization of an Rh-negative mother with a Rh-positive
ABO-compatible infant is 16% (2% of reactions will occur antepartum, 7%
within 6 months of delivery, and the remainder 7% in the second pregnancy)
MCCQE 2002 Review Notes
Obstetrics – OB19
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Pathophysiology
❏ maternal-fetal circulation normally separated by placental barrier
❏ upon first exposure, initially IgM and then IgG antibodies are produced
❏ sensitization routes
• incompatible blood transfusion
• previous fetal-maternal transplacental hemorrhage
• invasive procedure while pregnant
• therapeutic abortion, D&C, amniocentesis
• during labour and delivery
Diagnosis
❏ routine screening at first visit for blood group, Rh status, antibodies
❏ Ab titres < 1:16 considered benign
❏ Ab titres > 1:16 necessitates amniocentesis (correlation exists
between amount of biliary pigment in amniotic fluid and severity
of fetal anemia) from 27 weeks onwards
❏ Liley curve is used to determine bilirubin level and appropriate management
❏ Kleihauer-Betke test can be used to determine extent of fetomaternal hemorrhage
• fetal red blood cells are identified on a slide treated with citrate
phosphate buffer
• adult hemoglobin is more readily eluted through cell membrane
in presence of acid
❏ detailed U/S for fetal hydrops
Prophylaxis
❏ Rhogam binds to Rh Ag of fetus and prevents it from contacting
maternal immune system
❏ Rhogam (300 µg) must be given to all Rh negative women
• at 28 weeks
• within 72 hours of the birth of an Rh positive fetus
• with a positive Kleihauer-Betke test
• with any invasive procedure in pregnancy
• in ectopic pregnancy
• with miscarriage, therapeutic abortion (50 ug)
• with an antepartum hemorrhage
❏ if Rh neg and Ab screen positive, follow mother with serial monthly
Ab titres throughout pregnancy +/– serial amniocentesis as needed
(Rhogam of no benefit)
Management
❏ falling biliary pigment warrants no intervention (usually indicative
of fetus which is unaffected or mildly affected)
❏ rising or stable biliary pigment on serial amniocentesis must be
compared to a standard table which is divided into 3 zones based
on severity of hemolysis (Liley Curve)
❏ cordocentesis for fetal Hb; should be used cautiously, not first line
❏ intrauterine transfusion of O-negative packed red blood cells may be
required for severely affected fetus or early delivery of the fetus for
exchange transfusion
Complications
❏ anti-Rh IgG can cross the placenta and cause fetal RBC hemolysis resulting
in fetal anemia, CHF, edema, and ascites
❏ severe cases can lead to fetal hydrops (total body edema), or
erythroblastosis fetalis
INFECTIONS DURING PREGNANCY
❏ see table 6
OB20 – Obstetrics
MCCQE 2002 Review Notes
Protozoa
(Toxoplasma gondii)
ssRNA togavirus
DNA virus
(herpes family)
DNA virus
Treponema pallidum
DNA virus
Parvovirus B19
Retrovirus
Varicella zoster
virus (herpes family)
*Toxoplasmosis
*Rubella
*CMV
MCCQE 2002 Review Notes
*Herpes
Syphilis
Hepatitis B
Erythema
Infectiosum
(Fifth Disease)
HIV
Chicken Pox
T1
Direct, respiratory
Intimate contact with body
secretions, blood products,
vertical (12-28%)
Respiratory, infected blood
products, transplacental
Blood, saliva, semen,
vaginal secretions,
breast milk, transplacental
Transplacental
Intimate mucocutaneous
contact
13-30 weeks GA, and
5d pre to 2d post delivery
Greatest risk during L&D;
also transplacental
10-20 weeks GA
T3
10% vertical transmission
if asymptomatic HBsAg +ve;
85-90% if HBsAg and HBcAg +ve
T1-T3
C/S delivery (if genital lesions
present); less commonly in utero
Blood/organ transfusion,
T1-T3
sexual contact, breast milk,
transplacental, during delivery
Respiratory droplets
(highly contagious)
Raw meat, unpasteurized
goat’s milk, cat feces/urine
T3
(but most severe if infected in T1);
only concern if primary infection
during pregnancy
Greatest Transmission Risk
Agent
Infection
Source of Transmission
* indicates TORCH infection
Table 6. Infections During Pregnancy
Effects on Mother
Congenital varicella
syndrome (limb aplasia,
chorioretinitis, cataracts,
cutaneous scars, cortical
atrophy, IUGR, hydrops), PTL
Vertical transmission,
IUGR, PTL, PROM
SA, stillbirth, hydrops
in utero
Prematurity, low birth
weight, neonatal death
Risk of preterm labour,
multisystem involvement,
fetal death
Disseminated herpes (20%);
CNS sequelae (35%);
self-limited infection
5-10% develop CNS
involvement (MR, cerebral
calcification, hydrocephalus,
microcephaly, deafness,
chorioretinitis)
SA or congenital rubella
syndrome (hearing loss,
cataracts, CV lesions, MR,
IUGR, hepatitis, CNS defects,
osseous changes)
Fever, malaise,
vesicular pruritic lesions
See Infectious
Disease Chapter
Flu-like, rash, arthritis;
often asymptomatic
Fever, N/V, fatigue,
jaundice, increased LFTs
See Infectious
Disease Chapter
Painful vesicular lesions
Asymptomatic or flu-like
Rash (50%), fever,
posterior auricular
or suboccipital
lymphadenopathy,
arthralgia
Congenital toxoplasmosis
Majority subclinical;
(chorioretinitis, hydrocephaly, may have flu-like
intracranial cacification, MR,
symptoms
microcephaly)
NB: 75% initially
asymptomatic at birth
Effects on Fetus
C/S if active genital lesions,
even if remote from vulva
No specific treatment;
maintain good hygiene
and avoid high risk situations
No specific treatment; should
offer vaccine following
pregnancy (but avoid during
pregnancy as it is live
attenuated vaccine)
Self-limiting in mother;
spiramycin decreases fetal
morbidity
Treatment
Note: do not administer
vaccine during pregnancy
(live attenuated)
AZT decreases vertical
transmission (25 -> 8%)
All pregnancies
offered screening
Clinical, +/- vesicle
fluid culture,
+/– serology
If hydrops occurs, consider
fetal transfusion
Rx neonate with HBIG
and vaccine (at birth,
1, 6 mo); 90% effective
Serology, viral PCR,
maternal AFP; if IgM
present, follow fetus with
U/S for hydrops
Serologic screening
for all pregnancies
VDRL screening for all
Pen G 2.4 M units IM; monitor
pregnancies; confirm with VDRL monthly
TPHA or FTA-ABS
Clinical diagnosis
Serologic screen; isolate
virus from urine or
secretion culture
Serologic testing;
all pregnant women
screened (immune
if titre>1:16);
infection if IgM present
or >4X increase in IgG
IgM and IgG serology
confirm with IgM in
cord blood
Diagnosis
MEDICAL CONDITIONS IN PREGNANCY
. . . CONT.
Obstetrics – OB21
ANTENATAL HEMORRHAGE
FIRST AND SECOND TRIMESTER BLEEDING
Etiology
❏ abortion (threatened, inevitable, incomplete, complete)
• < 5% of threatened abortions go on to abort (see Table 7)
❏ abnormal pregnancy (ectopic, molar) (see Gynecology Chapter)
❏ trauma (post-coital)
❏ physiologic bleeding (due to placental development)
❏ genital lesion (e.g. cervical polyp, neoplasms)
Table 7. Types of Abortions
Type
History
Cervix
Management*
Threatened
Vaginal bleeding +/– cramps
Closed - intact
membranes
U/S shows viable fetus
Inevitable
Bleeding + cramps
+/– ruptured membranes
Open > 2 cm
D&C +/– oxytocin
Incomplete
Heaviest bleeding + cramps;
soft abdomen; may have
passage of tissue
Open
D&C +/– oxytocin
Complete
Bleeding + complete sac and
placenta passed
Open
No D&C
Missed
Fetal death and retention
of products; presents as
pregnancy not progressing
Closed
D&C +/– oxytocin
Habitual
3 or more consecutive
spontaneous abortions
Evaluate environmental factors
(smoking, alcohol, heavy caffeine),
uterine anatomy, karyotype of
both parents, TSH,
antiphospholipid antibodies
(including lupus anticoagulant
and anticardiolipin antibodies)
Therapeutic
For genetic, medical, and
psychological reasons
See below
Septic
Contents of uterus infected
before, during or after
abortion
D&C
IV wide spectrum antibiotics
Oxygen
* Rhogam to all Rh negative mothers
THERAPEUTIC ABORTIONS
❏ medical management
• < 9 weeks use methotrexate plus misoprostol
• > 12 weeks use prostaglandins intra- or extra-amniotically, or IM
❏ surgical management
• < 12-16 weeks use dilatation and curettage
• > 16 weeks use dilatation and evacuation
❏ complications
• pain, bleeding, low-grade fever
• perforation of uterus
• hemorrhage
• laceration of cervix
• risk of sterility
• infection/ endometritis - usually due to retained products
• Asherman syndrome (fibrosis of the uterus)
OB22 – Obstetrics
MCCQE 2002 Review Notes
ANTENATAL HEMORRHAGE
. . . CONT.
THIRD TRIMESTER BLEEDING
Etiology
❏ placenta previa
❏ abruptio placentae
❏ vasa previa
❏ bloody show (shedding of cervical mucous plug)
❏ marginal sinus bleeding
❏ cervical lesion (cervicitis, polyp, ectropion, cervical cancer)
❏ uterine rupture
❏ other: bleeding from bowel or bladder, placenta accreta, abnormal coagulation
RED FLAG
❏ Do NOT perform a vaginal exam until placenta previa has been ruled out by U/S
PLACENTA PREVIA (see Colour Atlas OB2)
Definition
❏ abnormal location of the placenta at or near the internal cervical os
❏ many are low lying in early pregnancy but due to development of lower
❏
❏
❏
❏
uterine segment appear to "move upward" as pregnancy nears term
total: placenta completely covers the internal os
partial: placenta partially covers the internal os
marginal: within 2 cm of os but does not cover any part of os
low lying (NOT a previa): placenta in lower segment but clear of os
• can also bleed, usually later (i.e. in labour)
Etiology
❏ incidence = 1/200 at time of delivery
❏ 90-95% of previas diagnosed in T2 resolve by T3
(repeat U/S at 30-32 weeks to follow migration)
❏ associated conditions and risk factors
• history of placenta previa (4-8% recurrence risk)
• multiparity
• increased maternal age
• multiple pregnancy
• uterine tumour (e.g. fibroids) or other uterine anomalies
• uterine scar due to previous abortion, C/S, D&C, myomectomy
Presentation
❏ recurrent, PAINLESS bright red vaginal bleeding
• onset of bleeding depends on degree of previa (i.e. complete bleed earlier)
• mean GA is 30 weeks; one third present earlier
• initially, bleeding may be minimal and cease spontaneously but can be catastrophic later
• bleeding at onset of labour can occur with marginal placenta previa
❏ uterus soft and non-tender
❏ presenting part high or displaced
Investigations
❏ ultrasound (transabdominal ultrasound has 95% accuracy)
Management
❏ stabilize and monitor
• maternal stabilization; large bore IV with hydration
• electronic fetal monitoring
• maternal monitoring: vitals, urine output, blood loss, bloodwork
(hematocrit, CBC, PTT/PT, platelets, fibrinogen, FDP, type and cross match)
❏ U/S assessment
• when fetal and maternal condition permit, perform careful U/S examination to
determine fetal viability, gestational age and placental status/position
❏ manage
• management decision depends on
• previa characteristics (amount of bleeding, degree of previa)
• fetal condition (GA, level of distress, presentation)
• uterine activity
• Rhogam if mother is Rh negative
• expectant management and observation of mother and fetus if the
initial bleeding episode is slight and GA < 37 weeks
• admit to hospital
• limited physical activity
• no douches, enemas, or sexual intercourse
• consider corticosteriods for fetal lung maturity
• delivery when fetus is mature or hemorrhage dictates
• C/S delivery if bleeding is profuse, GA > 36 weeks, or L/S ratio is
2:1 or greater (incision site dictated by location of previa)
MCCQE 2002 Review Notes
Obstetrics – OB23
ANTENATAL HEMORRHAGE
. . . CONT.
Complications
❏ fetal
❏ perinatal mortality low but still higher than with a normal pregnancy
• prematurity (bleeding often dictates early C/S)
• intrauterine hypoxia (acute or IUGR)
• fetal malpresentation
• PPROM
• risk of fetal blood loss from placenta, especially if incised during C/S
❏ maternal
• < 1% maternal mortality
• hemorrhage and hypovolemic shock
• anemia
• acute renal failure
• pituitary necrosis (Sheehan syndrome)
• post partum hemorrhage (because lower uterine segment is atonic)
• hysterectomy
• placenta accreta
ABRUPTIO PLACENTAE
Definition
❏ premature separation of a normally implanted placenta after 20 weeks gestation
❏ classification
• total (fetal death inevitable) vs. partial
• external/revealed/apparent; blood dissects downward toward cervix
• internal/concealed (20%); blood dissects upward toward fetus
• most are mixed
❏ incidence: 1/100 deliveries
Associated Conditions
❏ previous abruption (recurrence rate 10%)
❏ maternal hypertension (chronic or PIH) in 50% of abruptions
❏ maternal vascular disease
❏ cigarette smoking
❏ excessive alcohol consumption
❏ cocaine
❏ multiparity
❏ maternal age > 35 (felt to reflect parity)
❏ PPROM
❏ uterine distension (polyhydramnios, multiple gestation)
❏ sudden decompression of the uterus (twins)
❏ uterine anomaly, fibroids
❏ trauma (e.g. motor vehicle collision, maternal battering)
Presentation
❏ classically: PAINFUL vaginal bleeding, uterine tenderness, uterine contractions
❏ pain: sudden onset, constant, localized to lower back and uterus
❏ +/– fetal distress, fetal demise (15% present with demise), bloody amniotic fluid
Diagnosis
❏ clinical diagnosis
❏ ultrasound not sensitive for abruption (sensitivity = 15%)
Table 8. Grades of Abruptio Placentae
Grade
Uterine Irritability
Maternal Hemodynamics
Maternal Fibrinogen
FHR
Mild
Mild
Normal
Normal
Normal
Moderate Moderate-severe
+/- tetany
BP normal but with postural drop
Increased HR
9
Distress: loss
of variability,
late decels
Severe
Decreased BP
Increased HR
9 9
Fetal death
Tetany
OB24 – Obstetrics
MCCQE 2002 Review Notes
ANTENATAL HEMORRHAGE
. . . CONT.
Management
❏ stabilize and monitor
• maternal stabilization, IV hydration
• fetal monitoring
• monitor maternal vitals, urine output
• blood for hemoglobin, platelets, PT/PTT, fibrinogen, FDP, cross and type
• blood products on hand (red cells, platelets, cryoprecipitate) because of DIC risk
• Rhogam if Rh negative
❏ mild abruption and GA < 36 weeks
• close observation of fetal well-being and amount of bleeding
• limited physical activity
• serial Hct to assess concealed bleeding
• delivery when fetus is mature or when hemorrhage dictates
❏ mild abruption and GA > 36 weeks
• stabilization and delivery
❏ moderate to severe abruption
• hydrate and restore blood loss and correct coagulation defect if present
• vaginal delivery if no evidence of fetal or maternal distress and
if cephalic presentation OR with dead fetus
• labour must progress actively
❏ severe abruption and live fetus
• C/S if fetal or maternal distress develops with fluid/blood replacement,
labour fails to progress or non-cephalic fetal presentation
Complications
❏ fetal
• perinatal mortality 25-60%
• prematurity
• intrauterine hypoxia
❏ maternal
• < 1% maternal mortality
• DIC (in 20% of abruptions)
• acute renal failure
• anemia
• hemorrhagic shock
• pituitary necrosis (Sheehan syndrome)
• amniotic fluid embolus
VASA PREVIA
Definition
❏ velamentous insertion of cord into membranes of placenta;
unprotected fetal vessels pass over the cervical os
❏ 1 in 5,000 deliveries
Presentation
❏ painless vaginal bleeding and fetal distress (tachy- to bradyarrhythmia)
Investigations
❏ Apt test (NaOH mixed with the blood) can be done immediately to
determine if the source of the bleeding is fetal (supernatant turns pink)
or maternal (supernatant turns yellow)
❏ Wright stain on blood smear and look for nucleated red blood cells
(in cord not maternal blood)
Management
❏ emergent C/S
Complications
❏ 50% perinatal mortality, increasing to 75% if membranes rupture
(most infants die of exsanguination)
❏ since bleeding is from fetus, a small amount of blood loss can have catastrophic consequences
MCCQE 2002 Review Notes
Obstetrics – OB25
GROWTH DISCREPANCIES
INTRA-UTERINE GROWTH RESTRICTION (IUGR)
Definition
❏ infants whose weight is < 10th percentile for a particular GA
❏ weight not associated with any constitutional or familial cause
Etiology
❏ maternal causes
• poor nutrition, cigarette smoking, drug abuse, alcoholism,
cyanotic heart disease, severe DM, SLE, pulmonary insufficiency
❏ maternal-fetal
• any disease which causes placental insufficiency leading to
inadequate transfer of substrate across the placenta
• includes PIH, chronic HTN, chronic renal disease, gross placental
morphological abnormalities (infarction, hemangiomas)
❏ fetal causes
• TORCH infections, multiple gestation, congenital anomalies
Presentation
❏ symmetric/Type I (20%)
• occurs early in pregnancy
• inadequate growth of head and body although head:abdomen ratio may be normal
• usually associated with congenital anomalies or TORCH
❏ asymmetric/Type II (80%)
• occurs late in pregnancy
• brain is spared, therefore the head:abdomen ratio is increased
• usually associated with placental insufficiency
• more favorable prognosis than Type I
Investigations
❏ SFH measurements at every antepartum visit
❏ more thorough assessment if mother is in high risk category or if
SFH lags > 2 cm behind GA
❏ U/S exam should include assessment of BPD, head and abdomen
circumference, head:body ratio, femur length and fetal weight
❏ doppler analysis of umbilical cord blood flow
Management
❏ most important consideration is accurate menstrual history and GA
❏ prevention via risk modification prior to pregnancy ideal
❏ modify controllable factors: smoking, alcohol, nutrition
❏ bed rest (in LLD position)
❏ serial BPP (monitor fetal growth)
❏ delivery when extrauterine existence is less dangerous than continued intrauterine
existence or if GA > 34 weeks with significant oligohydramnios
❏ liberal use of C/S since IUGR fetus withstands labour poorly
Complications
❏ prone to meconium aspiration, asphyxia, polycythemia, hypoglycemia, and mental retardation
❏ greater risk of perinatal morbidity and mortality
MACROSOMIA
Definition
❏ fetal weight > 90th percentile for GA, or > 4,000 grams
Etiology
❏ risk factors
• obesity
• diabetes mellitus
• past history of macrosomic infant
• prolonged gestation
• multiparity
Investigations
❏ serial examination (SFH)
❏ investigations (U/S)
❏ U/S predictors: polyhydramnios, T3 AC growth > 1.5 cm/week, HC/AC
ratio < 10th percentile, FL/AC ratio < 20th percentile
Management
❏ C/S often safer than vaginal delivery
Complications
❏ increased risk of perinatal mortality
❏ fetopelvic disproportion and birth injuries (shoulder dystocia, fetal bone fracture)
more common
❏ complications of DM in labour (see Medical Conditions in Pregnancy section)
OB26 – Obstetrics
MCCQE 2002 Review Notes
GROWTH DSICREPANCIES
. . . CONT.
POLYHYDRAMNIOS
Definition
❏ amniotic fluid volume > 2,000 cc at any stage in pregnancy
❏ > 8 cm x 8 cm (3.1 x 3.1 in) pocket on U/S
Etiology
❏ incidence: 1/250 deliveries
❏ idiopathic: most common (40%)
❏ maternal
• Type 1 diabetes: causes abnormalities of transchorionic flow
❏ maternal-fetal
• chorioangiomas
• multiple gestation
• erythroblastosis
❏ fetal
• chromosomal anomaly (up to 2/3 of fetuses with severe polyhydramnios)
• respiratory - cystic adenomatoid malformed lung
• CNS (anencephaly, hydrocephalus, meningocele)
• GI (tracheoesophageal fistula, duodenal atresia)
• facial clefts, neck masses (interfere with swallowing)
Presentation
❏ pressure symptoms from overdistended uterus (dyspnea, edema, hydronephrosis)
❏ uterus large for dates, difficulty palpating fetal parts and hearing fetal heart tones
Management
❏ determine cause
• complete fetal U/S evaluation
• screen for maternal disease/infection as indicated
❏ management depends on severity
• mild to moderate cases require no treatment
• if severe, hospitalize and consider therapeutic amniocentesis
Complications
❏ cord prolapse
❏ placental abruption
❏ malpresentation
❏ preterm labour
❏ uterine dysfunction and postpartum hemorrhage (PPH)
❏ increased perinatal mortality rate
OLIGOHYDRAMNIOS
Definition
❏ amniotic fluid index of 5 cm (2 in) or less
Etiology
❏ early onset oligohydramnios
• decreased production
• renal agenesis or dysplasia, urinary obstruction,
posterior urethral valves (male)
• poor placental perfusion
• increased loss
• prolonged amniotic fluid leak (although most often labour ensues)
• 15-25% of cases have fetal anomalies
❏ late pregnancy onset oligohydramnios
• amniotic fluid normally decreases after 35 weeks
• common in post-term pregnancies
• may be a marker for infants who may not tolerate labour well
Management
❏ oligohydramnios is an important sign of chronic placental
insufficiency and always warrants admission and investigation
• rule out ROM
• fetal monitoring (NST, CTG, BPP)
• consider delivery if at term
Complications
❏ cord compression
❏ T1 onset
• Potter’s facies
• limb deformities
• abdominal wall defects
❏ onset at > 20 weeks
• pulmonary hypoplasia
MCCQE 2002 Review Notes
Obstetrics – OB27
ANTENATAL COMPLICATIONS
PRETERM LABOUR
Definition
❏ labour occurring between 20 and 37 weeks gestation
❏ preterm labour complicates about 10% of pregnancies
Etiology
❏ idiopathic (most common)
❏ maternal
• prior history of premature delivery (recurrence risk of 17-40%)
• history of abortions or stillbirths
• maternal age < 18 or > 40 years
• infection
• recurrent pyelonephritis and untreated bacteriuria
• maternal genital tract infection
• chorioamnionitis
• medical illness
• preeclampsia/hypertension
• uncontrolled diabetes
• other medical illness (heart disease, renal disease,
severe anemia, systemic infection, chronic vascular disease)
• mechanical
• fibroids or other uterine anomalies
• incompetent cervix
• previous incision into uterus or cervix (C/S, conization)
• surgical
• intra-abdominal surgery, cholecystitis, peritonitis
• social
• low socioeconomic status
• lack of prenatal care
• poor nutrition
• low prepregnancy weight
• smoking
• drug addiction (alcohol, cocaine)
• stress/anxiety/fatigue
❏ maternal-fetal
• PPROM (a common cause)
• polyhydramnios
• placenta previa or abruption
❏ fetal
• multiple gestation
• congenital abnormalities of fetus
Presentation
❏ regular contractions (2 in 10 minutes)
❏ cervix > 2 cm dilated or 80% effaced OR documented change in cervix
Management
❏ initial
• transfer to appropriate facility
• hydration (NS @ 150 mL/hour)
• bed rest in left lateral decubitus position
• sedation (morphine)
• avoid repeated pelvic exams (increased infection risk)
• U/S examination of fetus (for GA, BPP, position)
• prophylactic antibiotics; controversial but may help delay delivery,
also important to consider PPROM
❏ aggressiveness depends on the GA
❏ tocolytic agents - if no contraindications present; agent used depends on clinical situation
• do not inhibit preterm labour completely, but may buy time to allow
celestone use or to transfer to appropriate centre
• beta-mimetics: ritodrine, terbutaline
• magnesium sulfate (if diabetes or cardiovascular disease present)
• calcium channel blockers: nifedipine
• prostaglandin (PG) synthesis inhibitors (2nd line agent): indomethacin
❏ ensure availability of necessary personnel and equipment to assess mother and fetus
during labour and care for baby of the predicted GA if therapy fails
OB28 – Obstetrics
MCCQE 2002 Review Notes
ANTENATAL COMPLICATIONS
. . . CONT.
Requirements for Consideration of Labour Suppression (Tocolysis)
❏ live fetus
❏ fetal immaturity
❏ intact membranes
❏ cervical dilatation of 4 cm or less
❏ absence of maternal or fetal contraindications (see below)
Maternal Contraindications to Tocolysis
❏ bleeding (placenta previa or abruption)
❏ maternal disease (hypertension, diabetes, heart disease)
❏ preeclampsia or eclampsia
❏ chorioamnionitis
Fetal Contraindications to Tocolysis
❏ erythroblastosis fetalis
❏ severe congenital anomalies
❏ fetal distress/demise
❏ IUGR, multiple gestation (relative)
Enhancement of Pulmonary Maturity
❏ betamethasone valerate (Celestone) 12 mg IM q24h x 2
❏ most effective between 28 and 34 weeks gestation
❏ specific maternal contraindications: active TB, viral keratosis, maternal DM
Complications of Premature Labour
❏ prematurity is the leading cause of perinatal morbidity and mortality
• at 30 weeks or 1,500 g (3.3 lbs) = 90% survival
• at 33 weeks or 2,000 g (4.4 lbs) = 99% survival
❏ major causes of morbidity = asphyxia, sepsis, respiratory distress syndrome (RDS)
❏ intrapartum asphyxia may lead to cerebral hemorrhage
Prevention of Preterm Labour
❏ good prenatal care
❏ identify pregnancies at risk
❏ treat silent vaginal infection or UTI
❏ patient education
❏ the following may help but evidence for their effectiveness is lacking
• rest, time off work, stress reduction
• improved nutrition
• U/S measurement of cervical length or frequent vaginal exams to assess cervix;
this would catch PTL earlier so tocolysis would be more effective
RUPTURE OF MEMBRANES
Premature ROM (PROM)
❏ rupture of membranes prior to the onset of labour at any GA
Prolonged ROM
❏ if 24 hours elapse between rupture of membranes and onset of labour
Preterm ROM
❏ ROM occurring before 37 weeks gestation (associated with PTL)
Preterm Premature ROM (PPROM)
❏ rupture of membranes before 37 weeks AND prior to onset of labour
Risk Factors
❏ maternal
• multiparity
• cervical incompetence
• infection: cervicitis, vaginitis, STD, UTI
• family history of PROM
• low socioeconomic class/poor nutrition
❏ fetal
• congenital anomaly
• multiple gestation
❏ other risk factors associated with PTL (see above)
MCCQE 2002 Review Notes
Obstetrics – OB29
ANTENATAL COMPLICATIONS
. . . CONT.
Presentation
❏ history of fluid gush or continued leakage
Investigations
❏ sterile speculum exam (avoid introduction of infection)
• pooling of fluid in the posterior fornix
• may observe fluid leaking out of cervix on cough/valsalva (“cascade”)
❏ amniotic fluid turns nitrazine paper blue (low specificity as can be blood, urine or semen)
❏ ferning (high salt content of amniotic fluid evaporates and looks like ferns under microscope)
❏ U/S to R/O fetal anomalies, assess GA and amniotic fluid volume
Management
❏ avoid introducing infection with examinations (do not do a digital pelvic exam)
❏ cultures (cervix for GC, lower vagina for GBS)
❏ dependent upon gestational age; must weigh degree of prematurity vs
risk of amnionitis and sepsis by remaining in utero
• < 24 weeks consider termination (poor outlook due to pulmonary hypoplasia)
• 26-34 weeks: expectant management as prematurity complications are significant
• 34-36 weeks: “grey zone" where risk of death from RDS and neonatal sepsis is the same
• > 36 weeks: induction of labour since the risk of death from sepsis is greater than RDS
❏ assess fetal lung maturity by L/S ratio of amniotic fluid
❏ consider administration of betamethasone valerate (Celestone) to accelerate maturity
❏ if not in labour or labour not indicated, consider antibiotics (controversial)
❏ admit and monitor vitals q4h, daily BPP and WBC count
Complications
❏ cord prolapse
❏ intrauterine infection (chorioamnionitis)
❏ premature delivery
CHORIOAMNIONITIS
Definition
❏ infection of the chorion, amnion and amniotic fluid
Etiology/Risk Factors
❏ prolonged ROM
❏ long labour
❏ multiple vaginal exams during labour
❏ internal monitoring
❏ bacterial vaginosis and other vaginal infections
Presentation
❏ maternal fever, maternal or fetal tachycardia, uterine tenderness, foul cervical discharge
leukocytosis, presence of leukocytes or bacteria in amniotic fluid
Management
❏ blood and amniotic fluid cultures
❏ IV antibiotics (ampicillin and gentamycin)
❏ expedient delivery regardless of gestational age
POST-DATE PREGNANCY
Definition
❏ pregnancy beyond 42 weeks
❏ accurate dating essential
❏ 10% of pregnancies
Management
❏ fetal movement count by the mother
❏ BPP twice weekly from 40 weeks (if BPP < 10/10 at any time, deliver)
❏ deliver after 41 weeks (induction or C/S) if not already in labour since perinatal
mortality is higher secondary to progressive uteroplacental insufficiency
OB30 – Obstetrics
MCCQE 2002 Review Notes
ANTENATAL COMPLICATIONS
. . . CONT.
Complications
❏ perinatal mortality 2-3x higher
❏ oligohydramnios
❏ meconium passage: risk of meconium aspiration
❏ asphyxia
❏ macrosomia
❏ placental insufficiency; infarction of aging placenta
❏ postmaturity syndrome:10-20% of post-term pregnancies (fetal weight loss, reduction
in subcutaneous fat, scaling, dry skin from placental insufficiency)
❏ morbidity increased with hypertension/PET, DM, abruption, IUGR and multiple gestation
INTRAUTERINE FETAL DEATH
❏ 1% of pregnancies
Etiology
❏ unknown in 50%
❏ hypertension, DM
❏ erythroblastosis fetalis
❏ congenital anomalies
❏ umbilical cord or placental complications
❏ intrauterine infection
❏ antiphospholipid Abx
Presentation
❏ decreased perception of fetal movement by mother
❏ SFH and maternal weight not increasing
❏ absent fetal heart tones (not diagnostic)
❏ absent cardiac activity and fetal movement on U/S required for diagnosis
❏ high MSAFP
Investigations (To Determine Cause)
❏ maternal: HbA1c, Kleihauer-Betke, VDRL, ANA, anti-cardiolipin antibodies,
PTT, serum/urine toxicology screens
❏ fetal: chromosomes, cord blood, skin biopsy, genetics evaluation (dysmorphology), autopsy
❏ placenta: pathology
Management
❏ labour induction
❏ monitor for maternal coagulopathy (10% risk of DIC)
❏ psychologic aspects of fetal loss
NORMAL LABOUR AND DELIVERY
THE FETUS
Fetal Lie
❏ refers to the orientation of the long axis of the fetus with respect to
the long axis of the uterus (longitudinal, transverse, oblique)
❏ transverse/oblique often due to uterine anomalies (C/S if they don’t convert)
Fetal Presentation
❏ refers to the fetal part presenting at pelvic outlet
• breech (complete, frank, footling) (Figure 7)
• cephalic
• vertex (area between fontanelles and laterally by parietal eminences)
• brow/sinciput
• face
• shoulder
• compound (fetal extremity prolapses along with presenting part)
❏ all except vertex are considered malpresentations (see Abnormal Labour section)
Fetal Position
❏ refers to position of fetal occiput in relation to maternal pelvis
• occiput anterior (OA): commonest presentation (“normal")
• occiput posterior (OP): most rotate spontaneously to OA;
may cause prolonged second stage of labour
• occiput transverse (OT): leads to arrest of dilatation
❏ normally, fetal head enters maternal pelvis and engages in OT position
subsequently rotates to OA position or OP (in a small percentage of cases)
MCCQE 2002 Review Notes
Obstetrics – OB31
NORMAL LABOUR AND DELIVERY
. . . CONT.
Attitude
❏ refers to flexion/extension of fetal head relative to shoulders
• brow presentation: head partially extended (requires C/S)
• face presentation: head fully extended (mentum posterior always
requires C/S, mentum anterior will deliver vaginally)
Station
❏ refers to position of presenting part relative to ischial spines
• at ischial spines = station 0 = engaged
• 2 cm below ischial spines = station +2
THE CERVIX
❏
❏
❏
❏
❏
❏
dilatation: latent phase: 0-3 cm; active phase: 4-10 cm
effacement: thinning of the cervix (25%-50%-100%)
consistency: soft vs. hard
position: posterior vs. anterior
application: contact between the cervix and presenting part
Note: For Bishop Score, see Induction of Labour section
DEFINITION OF LABOUR
❏ progressive DILATATION and EFFACEMENT of cervix,
normally associated with DESCENT of presenting part
• preterm (> 20 but < 37 weeks GA)
• term (37-42 weeks)
• post-term (> 42 weeks)
❏ Braxton-Hick contractions
• irregular, occur throughout pregnancy and not associated with any
dilatation, effacement or descent
FOUR STAGES OF LABOUR
First Stage of Labour
❏ latent phase
• uterine contractions typically infrequent and irregular
• slow cervical dilatation (usually to 3-4 cm) and effacement
❏ active phase
• rapid cervical dilatation to full dilatation
(nulliparous ~1.2 cm/h and ~1.5 cm/h in multiparous)
• phase of maximum slope on Friedman curve (see Figure 6)
• painful, regular contractions ~q2 min, lasting 45-60 seconds
• contractions strongest at fundus, weakest at lower segment
Second Stage of Labour
❏ from full dilatation to delivery of the baby
❏ mother feels a desire to bear down and push with each contraction
❏ progress measured by descent
Third Stage of Labour
❏ separation and expulsion of the placenta
❏ can last up to 30 minutes before intervention indicated
❏ signs of placenta separation: gush of blood, lengthening of cord,
uterus becomes globular and fundus rises
Fourth Stage of Labour
❏ first postpartum hour
❏ monitor vital signs and bleeding +/– oxytocin
❏ repair lacerations
❏ ensure uterus is contracted (palpate uterus and monitor uterine bleeding)
❏ 3rd and 4th stages of labour most dangerous to the mother (i.e. hemorrhage)
Table 9. Course of Normal Labour
Stage
Nulliparous
Multiparous
First
6-18 hours
2-10 hours
Second
30 minutes-3 hours
5-30 minutes
Third
5-30 minutes
5-30 minutes
OB32 – Obstetrics
MCCQE 2002 Review Notes
NORMAL LABOUR AND DELIVERY
. . . CONT.
CARDINAL MOVEMENTS OF THE FETUS DURING DELIVERY
❏
❏
❏
❏
❏
❏
❏
Engagement
Descent
Flexion
Internal Rotation (to OA position ideally)
Extension (delivery of head)
External Rotation (restitution); head rotates in line with the shoulders
Expulsion (delivery of shoulders and body)
Figure 5. Movements of the Fetus During Labour and
Delivery, Left Occiput Anterior Position
(Reproduced with permission from Cunningham FG, MacDonald PC, Leveno KJ et al (eds): Williams
Obstetrics. 19Th ed. Stanford, Appleton and Lange, 1993)
MCCQE 2002 Review Notes
Obstetrics – OB33
ABNORMAL LABOUR
INDUCTION OF LABOUR
Definition
❏ the artificial initiation of labour to maintain maternal health or to remove
the fetus from a potentially harmful environment
Prerequisites for Labour Induction
❏ maternal
• short anterior cervix with open os (“inducible" or “ripe”)
• if cervix is not ripe, use prostaglandin (PG) gel (see below)
❏ fetal
• adequate fetal monitoring available
• cephalic presentation
• good fetal health
❏ likelihood of success determined by Bishop Score (see Table 10)
• score of 9-13 associated with high likelihood of vaginal delivery
Table 10. Bishop Score
Cervical characteristic
Position
Consistency
Effacement (%)
Dilatation (cm)
Station of fetal head
0
Posterior
Firm
0-30
0
–3
1
Mid
Medium
40-50
1-2
–2
2
Anterior
Soft
60-70
3-4
–1
3
–
–
> 80
≥5
+1
Indications
❏ maternal factors
• pregnancy-induced hypertension
• maternal medical problems, e.g. diabetes, renal or lung disease
❏ maternal-fetal factors
• Rh isoimmunization
• PROM
• chorioamnionitis
• post-term pregnancy
❏ fetal factors
• suspected fetal jeopardy as evidenced by biochemical or biophysical indications
• fetal demise
Contraindications
❏ maternal
• prior classical incision or complete transection of the uterus
• unstable maternal condition
• gross cephalopelvic diameter (CPD)
• active maternal genital herpes
❏ maternal-fetal
• placenta or vasa previa
❏ fetal
• distress
• malpresentation
• preterm fetus without lung maturity
INDUCTION METHODS
Cervical Ripening
❏ PG synthesized by cervical cells and in amniotic fluid to facilitate
labour onset and progression
❏ PG gel used to augment slow or arrested cervical dilatation or effacement
• intracervical dinoprostone (Prepidil) when cervix long and
closed and no ROM
• vaginal (Cervidil) when cervix favorable, may use with ROM
• use associated with reduced rate of C/S, instrumental vaginal
delivery, and failed induction
• risks include hyperstimulation and fetal heart rate abnormalities
• obtain reactive NST prior to administration
❏ other methods include placement of Foley catheter to mechanically
dilate the cervix, or the use of osmotic dilators (laminaria)
OB34 – Obstetrics
MCCQE 2002 Review Notes
ABNORMAL LABOUR . . . CONT.
Medical
❏ oxytocin/pitocin: start at 0.5-2 mU/minute IV, increasing by 1-2 mU/minute
q20-60 minutes to a maximum of 36-48 mU/minute
❏ potential complications
• hyperstimulation/tetanic contraction (may cause fetal distress or rupture of uterus)
• uterine muscle fatigue, uterine atony (may result in PPH)
• vasopressin-like action causing anti-diuresis
❏ PGF-2 alpha used for intrauterine fetal demise (IUFD)
Surgical
❏ artificial rupture of membranes (amniotomy) to stimulate PG synthesis and secretion;
may try this as initial measure
AUGMENTATION OF LABOUR
❏ augmentation of labour is used to promote adequate contractions
when spontaneous contractions are inadequate and cervical
dilatation or descent of fetus fails to occur
❏ oxytocin 2 mU/minute IV, increased by 1-2 mU/minute
q20-60 minutes to a maximum of 36-48 mU/minute
❏ half-life of oxytocin is 3-5 minutes (thus need continuous drip because effects wear off fast)
ABNORMAL PROGRESSION OF LABOUR
❏ expected patterns of descent of the presenting part and cervical
dilatation fail to occur in the appropriate time frame (see Figure 6)
❏ can occur in all stages of labour
❏ traditionally three causes of abnormal labour have been recognized
• Power: poor, inadequate or uncoordinated uterine contractions
• Passenger: fetus too large in size or unusual presentation
• Passage: cephalopelvic disproportion (CPD) = pelvis of
inadequate size, shape or consistency, or maternal soft
tissue resistance relative to fetus
❏ initial diagnosis of CPD requires progression into the
active phase and the presence of adequate uterine contractions
Cervical
Dilatation
(cm)
Figure 6. Normal and Abnormal Courses of the First
Stage of Labour (Friedman Curve)
Arrest Disorder (Curve C)
❏ of dilatation: progress in dilatation does not occur for a period
of 2 hours or more in a patient who has entered the active phase
• arrest usually occurs at a cervical dilatation of 5 to 8 cm
❏ of descent: no progress in station for > 1 hour during second stage
• should search for factors causing CPD (nearly 50%; requires C/S)
• CPD diagnosed if adequate contractions measured by intrauterine
pressure catheter (IUPC) with no descent/dilatation for > 2 hours
❏ if CPD ruled out, IV oxytocin and amniotomy can be attempted
Protraction Disorders (Curve D)
❏ of dilatation: when slope of cervical dilatation is less than
1.2 cm/hour in the primigravida or 1.5 cm/hour in the multigravida
❏ of descent: a rate of descent of less than 1.0 cm/hour in the primigravida or 2.0 cm/hour in the multigravida
❏ in about 1/3 of protraction disorders CPD will be present so that secondary arrest of dilatation
usually develops
❏ 2/3 of protraction disorders will progress steadily through labour with ultimate uneventful vaginal delivery
❏ treatment: oxytocin augmentation if contractions are inadequate and/or amniotomy
MCCQE 2002 Review Notes
Obstetrics – OB35
ABNORMAL LABOUR . . . CONT.
Prolonged Latent Phase (Curve E)
❏ a period of 20 hours or more in the primigravida or 14 hours or more in the
multigravida during which labour has not progressed to the active phase
❏ most often patient not really in labour (avoid amniotomy for fear of
false labour and increased risk of intrauterine infection)
❏ premature or excessive use of sedation or analgesia commonly seen in these patients
❏ careful search for factors of CPD should be made
❏ treatment: oxytocin augmentation if diagnosis of labour is certain,
otherwise rest +/– sedation
UMBILICAL CORD PROLAPSE
Definition
❏ descent of the cord to a level adjacent to or below the presenting part
causing cord compression between presenting part and pelvis
Etiology/Epidemiology
❏ increased incidence with prematurity/PROM, fetal malpresentations,
low-lying placenta, polyhydramnios, multiple gestation, CPD
Presentation
❏ visible or palpable cord
❏ FHR changes (variable decelerations, bradycardia or both)
Management
❏ emergent C/S
❏ adjunctive measures
• alleviate pressure of the presenting part on the cord
• keep cord warm and moist by replacing it into the vagina and/or
applying warm saline soaks
SHOULDER DYSTOCIA
Definition
❏ impaction of anterior shoulder of fetus against symphysis pubis after
fetal head has been delivered (life threatening emergency)
Etiology/Epidemiology
❏ incidence is 0.15-1.4% of deliveries
❏ occurs when breadth of shoulders is greater than biparietal diameter of the head
❏ risk factors
• maternal
• maternal obesity
• diabetes
• multiparity
• fetal
• prolonged gestation
• macrosomia
• labour
• prolonged 1st and 2nd stages
• prolonged deceleration phase (8-10 cm)
• instrumental midpelvic delivery
Presentation
❏ watch for “turtle sign” (head advances during contraction but returns to previous position
at end of contraction)
Complications
❏ chest compression by vagina or cord compression by pelvis can lead to hypoxia
❏ danger of brachial plexus injury (Erb palsy)
❏ fetal fracture (clavicle, humerus, cervical spine)
❏ maternal perineal injury, may result in PPH
OB36 – Obstetrics
MCCQE 2002 Review Notes
ABNORMAL LABOUR . . . CONT.
Management
❏ goal: to displace anterior shoulder from behind symphysis pubis;
follow a stepwise approach of maneuvers until goal achieved
A: apply suprapubic pressure
A: ask for help
L: legs in full flexion (McRobert’s maneuver)
A: anterior shoulder disimpaction
R: release posterior shoulder
M: maneuver of Wood’s corkscrew
E: episiotomy
❏ Other (last resort)
• cleidotomy: deliberate fracture of the clavicle
• Zavanelli maneuver: replacement of fetus into uterine cavity and emergent C/S
BREECH PRESENTATION
Definition
❏ fetal buttocks or lower extremity is the presenting part (Figure 7)
❏ complete: flexion at hips and knees
❏ frank: flexion at hips, extension at knees
• most common type of breech presentation
• most common breech presentation to be delivered vaginally
❏ footling: may be single or double with extension at hip(s) and knee(s)
so that foot is the presenting part
Etiology/Epidemiology
❏ occurs in 3-4% of pregnancies at term (25% before 28 weeks)
❏ risk factors
• maternal risk factors
• pelvis (contracted)
• uterus (shape abnormalities, intrauterine tumours, fibroids
extrauterine tumours causing compression)
• grand multiparity
• maternal-fetal
• placenta (previa)
• amniotic fluid (poly/oligohydramnios)
• fetal
• prematurity
• multiple gestation
• congenital malformations (found in 6% of breeches; 2-3x the
incidence in vertex presentations)
Presentation
❏ noted by Leopold maneuvers and U/S
Management
❏ extenal breech version
• criteria: > 37 weeks, singleton, unengaged presenting part, reactive NST
• contraindications: previous T3 bleed, prior classical C/S, previous
myomectomy, oligohydramnios, PROM, placenta previa, abnormal
U/S, suspected IUGR, hypertension, uteroplacental insufficiency
• risks: abruption, cord compression
• method: tocometry, followed by ultrasound guided transabdominal
manipulation of fetus
• if patient Rh negative, give Rhogam prior to procedure
• good prognostic factors (for a successful version)
• multiparous
• good fluid volume
• small baby
• skilled obstetrician
❏ criteria for vaginal delivery
• frank or complete breech, GA > 36 weeks
• estimated birth weight (EBW) 2,500-3,800 g based on clinical and U/S assessment (5.5-8.5 lb)
• fetal head flexed
• continuous fetal monitoring
• maternal pelvis adequately large (clinically, or “proven” by previous delivery)
• no other indication for C/S
• experienced obstetrician, assistant, and anesthetist present
MCCQE 2002 Review Notes
Obstetrics – OB37
ABNORMAL LABOUR . . . CONT.
❏ C/S for all other presentations (except mentoanterior face presentation)
❏ C/S is recommended if the breech has not descended to the perineum in the second stage of labour after
two hours, in the absence of active pushing, or if vaginal delivery is not imminent after one hour of
active pushing
❏ a recent randomized multicentre trial (Toronto, CA) has demonstrated that for women with frank or complete
breech presentations, perinatal mortality, neonatal mortality, and serious neonatal morbidity is significantly
lower for those with planned C/S over those with planned vaginal birth, with no significant difference
in maternal complications
A. Complete Breech
B. Frank Breech
C. Footling Breech
Figure 7. Types of Breech Presentation
Illustration by Jennifer Bosy
VAGINAL BIRTH AFTER CESAREAN (VBAC)
❏ recommended after previous low transverse incision
❏ success rate varies with indication for previous C/S (generally 60-80%)
❏ risk of uterine rupture (< 1% with low transverse incision)
Contraindications (i.e. need to do a repeat C-section before onset of labour)
❏ previous classical, inverted T, or unknown uterine incision,
or complete transection of uterus (6% risk of rupture)
❏ history of hysterotomy or previous uterine rupture
❏ multiple gestation
❏ estimated fetal weight > 4,000 g (9 lbs)
❏ non-vertex presentation or placenta previa
❏ inadequate facilities or personnel for emergency C/S
UTERINE RUPTURE
❏ associated with previous uterine scar (in 40% of cases), hyperstimulation with oxytocin,
grand multiparity and previous intrauterine manipulation
❏ generally occurs during labour, but can occur earlier with a classical incision
Management
❏ immediate delivery for fetal survival
❏ maternal stabilization (may require hysterectomy)
Complications
❏ maternal mortality 1-10%
❏ maternal hemorrhage and shock
❏ DIC
❏ amniotic fluid embolus
❏ hysterectomy
❏ fetal distress ––> 50% mortality
AMNIOTIC FLUID EMBOLUS
Definition
❏ amniotic fluid debris in maternal circulation
Etiology/Epidemiology
❏ rare intrapartum or immediate postpartum complication
❏ 80% mortality
❏ risk factors
• placental abruption
• rapid labour
• multiparity
• uterine rupture
Presentation
❏ sudden onset of respiratory distress, cardiovascular collapse and coagulopathy
Management
❏ supportive measures, coagulopathy correction
OB38 – Obstetrics
MCCQE 2002 Review Notes
OPERATIVE OBSTETRICS
❏ operative vaginal delivery = forceps or vacuum extraction
INDICATIONS FOR OPERATIVE VAGINAL DELIVERY
❏ fetal
• non-reassuring fetal status
• consider if second stage is prolonged as this may be due to poor
contractions or failure of fetal head to rotate
❏ maternal
• need to avoid voluntary expulsive effort (cardiac/cerebrovascular disease)
• exhaustion, lack of cooperation and excessive analgesia may impair pushing effort
FORCEPS
Outlet Forceps
❏ head visible between labia in between contractions
❏ sagittal suture in or close to A-P diameter
❏ rotation cannot exceed 45 degrees
Low Forceps
❏ presenting part at station +2 or greater
❏ similar to outlet forceps
❏ subdivided based on whether rotation less than or greater than 45 degrees
Mid Forceps
❏ presenting part below spines but above station +2
Types of Forceps
❏ Simpson forceps for OA presentations
❏ rotational forceps (Kjelland) when must rotate head to OA
❏ Piper forceps for breech
Prerequisites
A: anesthesia
B: bladder empty
C: cervix fully dilated
D: determine position of fetal head
E: equipment ready (including facilities for emergent C/S)
F: fontanelle (“Position For Safety” is posterior fontanelle midway
between shanks, fenestration barely palpable)
G: gentle traction
H: handle elevated
I: incision (episiotomy)
J: once jaw visible, remove forceps
(modified from J. Bachman, 1989)
Complications
❏ maternal: anesthesia risk, lacerations, injury to bladder, uterus, bone,
pelvic nerve damage, PPH, infections
❏ fetal: fractures, facial nerve palsy, trauma to face/scalp, intracerebralhemorrhage (ICH),
cephalohematoma, cord compression
VACUUM EXTRACTION
❏ traction instrument used as alternative to forceps delivery; aids maternal pushing
❏ same indications as forceps
❏ advantages
• easier to apply
• less force on fetal head
• less anesthesia required
• less maternal and fetal injury
• will lose suction and dislodge if unrecognized CPD present
❏ disadvantages
• suitable only for vertex presentations
• maternal pushing required
• contraindicated in preterm delivery
MCCQE 2002 Review Notes
Obstetrics – OB39
OPERATIVE OBSTETRICS . . . CONT.
LACERATIONS
❏ first degree
• involves skin and vaginal mucosa but not underlying fascia and muscle
❏ second degree
• involves fascia and muscles of the perineal body but not the anal sphincter
❏ third degree
• involves the anal sphincter but does not extend through it
❏ fourth degree
• extends through the anal sphincter into the rectal mucosa
EPISIOTOMY
Definition
❏ incision in the perineal body at the time of delivery
❏ midline: incision through central tendinous portion of perineal body and though bulbocavernosus muscle;
better healing but increased risk of deep tear
❏ mediolateral: incision through bulbocavernosus, transverse perineal muscle, and levator ani;
reduced risk of extensive tear but poorer healing and more pain
Indications
❏ to prevent a tear (episiotomy easier to repair)
❏ to relieve obstruction of the unyielding perineum
❏ instrumental delivery
❏ controversy over whether it is preferable to make a cut, or let the perineum tear as needed;
current evidence suggests we should generally let patients tear
CESAREAN DELIVERY
Indications
❏ maternal
• obstruction, active herpetic lesion on vulva, invasive cervical cancer, previous uterine surgery,
underlying maternal illness (eclampsia, HELLP syndrome, heart disease)
❏ maternal-fetal
• failure to progress, placental abruption or previa
❏ fetal
• fetal distress, malpresentation, cord prolapse, certain congenital anomalies
Risks
❏ anesthesia
❏ hemorrhage
❏ infection (UTI, wound, endometritis)
❏ injury to surrounding structures
❏ thromboembolic phenomena
❏ increased recovery time/hospital stay
OBSTETRICAL ANESTHESIA
PAIN PATHWAYS DURING LABOUR
❏ early first stage: pain via visceral afferents enter the spinal cord at T10-L1
• dilatation of the cervix
• lower uterine distension
• contraction of the uterus
❏ late first stage and second stage pain via visceral and somatic afferents
(pudendal nerve) enter the spinal cord at S2-S4
• contraction of the uterus
• distension and stretching of pelvic structures (pelvic
peritoneum, fascia, ligaments, and muscles)
• pressure on lumbar nerves
❏ third stage of labour is usually well tolerated with spontaneous placental delivery
• analgesia may be necessary for manual extraction of placenta
OB40 – Obstetrics
MCCQE 2002 Review Notes
OBSTETRICAL ANESTHESIA . . . CONT.
ANALGESIA
Psychoprophylaxis and Physical Analgesia
❏ “natural childbirth” (e.g. Lamaze prenatal classes) whereby an informed mother utilizes relaxation
techniques to stimulate the descending inhibitory pathways
❏ whirlpool baths, transcutaneous nerve stimulation (TNS), and acupuncture
inhibit nociceptive impulses and reduce pain propagating muscle tension
❏ especially effective in early stages of labour
Intravenous Analgesia
❏ meperidine (Demerol)
• best used in early stages of labour, less effective once labour is well established
• rapidly cleared by fetus if IV (prolonged if IM)
• peak fetal level 2-4 hours after maternal injection IM
• can suppress respiration in the newbom (treat with naloxone)
• side effects: orthostatic hypotension, nausea, and vomiting
Inhalational Analgesia
❏ nitrous oxide
• 50% nitrous oxide in O2
• self-administered during contractions
• does not prolong labour or interfere with uterine contractions
but administration > 20 minutes may result in neonatal depression
• provides partial pain relief during labour as well as at delivery
ANESTHESIA
Local Perineal Anesthesia
❏ local blocks
❏ lidocaine for episiotomy
❏ pudendal blocks
Regional Anesthesia
❏ epidural
• most commonly used technique for both labour and delivery
• does not prolong first stage, but may reduce maternal expulsive
efforts, therefore usually used in earlier stages of labour (< 4 cm)
• 0.25% bupivacaine (Marcaine) usually used for labour
(longer acting compared to lidocaine and less motor block)
• 2% lidocaine (Xylocaine) usually used for vaginal deliveries
and C/S in varying doses
• 19 gauge indwelling catheter inserted into lumbar epidural space
• preload mother with 500-1000 mL IV fluid to prevent
maternal hypotension associated with epidural
(fetal depression rare if maternal hypotension avoided)
• test dose given first to check for spinal block followed by
another dose to rule out intravascular injection;
if no dizziness or tinnitus, rest of dose is given
• complications: inadvertent total spinal with cardiovascular
collapse and respiratory arrest, inadvertent intravascular injection
with seizures, post-ictal depression and possible cardiac arrest
❏ walking epidural
• goal is effective analgesia with no motor blockade
• 0.125% bupivacaine plus low dose fentanyl
❏ spinal block
• for C/S need anesthesia of T4-T8
• injection of local anesthetic into subarachnoid space
• fastest onset
• least drug exposure for fetus because small dose required
• not appropriate for labour due to intense motor blockade
• beware of rapid hypotension and preload mother with 1,000 mL fluid
General Anesthesia
❏ not used for vaginal deliveries, but may be used for C/S in certain circumstances
❏ rapid sequence induction to prevent aspiration
❏ pre-oxygenate mother with 100% O2 as she is prone to hypoxia during
intubation secondary to decreased FRC and increased O2 consumption
MCCQE 2002 Review Notes
Obstetrics – OB41
NORMAL PUERPERIUM
DEFINITION
❏ period of adjustment after pregnancy when pregnancy-induced anatomic
and physiologic changes are reversed
❏ traditionally, puerperium lasts 6 weeks
POST-DELIVERY EXAMINATION
❏ The 8 Bs: Blues (post-partum), Breathing (DVT/PE), Breast, Belly,
Bowels, Bladder, Bleeding, Baby
BREAST
❏ 2 events stimulate lactation
• sudden drop in placental hormones (especially estrogen)
• suckling stimulates release of prolactin and oxytocin
❏ colostrum secreted for ~ 2 days after delivery (contains protein, fat, minerals, IgA)
• replaced by milk after ~ 3-6 days (contains protein, lactose, water, fat)
❏ breast-feeding encouraged (see Pediatrics Chapter)
UTERUS
❏ through process of catabolism, uterus weight rapidly diminishes
❏ cervix loses its elasticity and regains firmness
❏ start oxytocin drip or give oxytocin 10 U IM after 3rd stage
(i.e. after delivery of placenta; some give IM dose after delivery of head)
❏ generally should involute ~ 1 cm (1 finger breadth) below umbilicus per day in first 4-5 days
❏ involution then slows down; reaches non-pregnant state in 4-6 weeks postpartum
LOCHIA (Normal Vaginal Discharge Postpartum)
❏ monitored for signs of infection or bleeding
❏ normally decreases and changes colour from red (lochia rubra; due to presence of erythrocytes)
to yellow (lochia serosa) to white (lochia alba; residual leukorrhea) over 3-6 weeks
❏ foul smelling lochia suggests endometritis
POSTPARTUM CARE
❏
❏
❏
❏
❏
❏
bowel- encourage plenty of fluids and high-fibre foods, bulk laxatives may be helpful
bladder: maintain high fluid intake
sex: wait until 4-6 weeks post-delivery
hemorrhoids/perineal tenderness: pain meds, doughnut cushion, Sitz baths, ice compresses
exercise: encourage gradual increases in walking, Kegel exercises
do not use douches or tampons for 4-6 weeks post-delivery
PUERPERAL COMPLICATIONS
RETAINED PLACENTA
Definition
❏ placenta undelivered after 30 minutes
Etiology/Epidemiology
❏ placenta separated but not delivered, or abnormal placental implantation
• placenta accreta: placenta adherent to myometrium
• placenta increta: invasion of myometrium
• placenta percreta: invasion of myometrium beyond serosa
❏ risk factors: placenta previa, prior C/S, post-pregnancy curettage,
prior manual placental removal, uterine infection
Management
❏ 2 large bore IVs, type and screen
❏ perform Brant maneuver (firm traction on umbilical cord with one hand
applying pressure suprapubically to hold uterus in place)
❏ oxytocin 10 IU in 20 mL NS into umbilical vein
❏ manual removal if above fails
❏ D&C if required
Complications
❏ increased risk of infection or bleeding
OB42 – Obstetrics
MCCQE 2002 Review Notes
PUERPERAL COMPLICATIONS . . . CONT.
UTERINE INVERSION
Definition
❏ uterus prolapses through the cervix and passes out of the vaginal introitus
Etiology
❏ often iatrogenic (excess cord traction)
❏ more common in grand multiparous (lax uterine ligaments)
❏ can cause profound vasovagal response with vasodilation and hypovolemic shock
Management
❏ urgent management essential (may require general anesthetic if unsuccessful)
❏ call anesthesia
❏ initiate IV crystalloids
❏ replace uterus without removing placenta
❏ remove placenta manually and withdraw slowly
❏ can use tocolytic drug (e.g. terbutaline) to relax uterus
❏ IV oxytocin infusion
❏ re-explore uterus
❏ may require GA +/– surgery
POSTPARTUM PYREXIA
Definition
❏ fever > 38.0ºC on any 2 of the first 10 days postpartum, except the first day
Causes
❏ wind (atelectasis, pneumonia)
❏ water (UTI)
❏ wound (gram +/–, aerobes, and anaerobes)
• C/S incision site
• episiotomy site
• empiric treatment: clindamycin + gentamicin
• prophylaxis against post-C/S endometritis
• begin antibiotic immediately after cord clamping and administer only 1-3 doses
• cefazolin is most common
❏ walking
• pelvic thrombophlebitis (diagnosis of exclusion)
• DVT
❏ breast
• engorgement may cause slight physiologic temperature rise on first day
• mastitis (Staphylococcus aureus most common)
❏ endometritis
• blood and genital cultures
POSTPARTUM HEMORRHAGE (PPH)
Definition
❏ loss of > 500 mL of blood at the time of vaginal delivery, or > 1,000 mL with C/S
Etiology (4 Ts)
❏ Tone: uterine atony (most common cause of PPH; try to avoid by giving
IV oxytocin with delivery of the anterior shoulder)
• occurs within first 24 hours
• labour (prolonged, precipitous)
• uterus (infection, over-distension)
• placenta (abruption, previa)
• maternal factors (grand multiparity, GA)
• halothane anesthesia
❏ Tissue: retained placenta (see above)
❏ Trauma: laceration (vagina, cervix, uterus), episiotomy, hematoma, uterine rupture, uterine inversion
(see above)
❏ Thrombin: coagulopathy
• most identified prior to delivery (low platelets increases risk)
• includes hemophilia, DIC, aspirin use, ITP, TTP, VWD (most common)
• monitor fibrinogen, platelets
Investigations
❏ pelvic U/S if indicated to look for cause if unknown
MCCQE 2002 Review Notes
Obstetrics – OB43
PUERPERAL COMPLICATIONS . . . CONT.
Management
❏ determine cause, call for help
❏ supportive
• ABCs, fluid, cross and type 4 units PRBC
❏ examination
• reexamine patient, ensure complete delivery of placenta
• check for uterine atony and drain bladder
• check for cervical and vaginal lacerations
• elevate the uterus and massage through patient's abdomen
❏ medical
• oxytocin (5 U IV push then 40 U/L NS drip)
• methylergonavine maleate (ergotamine; 0.2 mg PO or 0.25 mg IM)
(normotensive patients only; must explore uterus before giving ergotamine)
• prostaglandins (PGF-2 alpha intrauterine or IM, misoprostol)
• hemabate (prostaglandin; 0.25-1.00 mg intramyometrium every 15 minutes)
• uterine packing (3-4 five yard Kerlex rolls tied together and
soaked in betadine and removed in 12-24 hours; controversial)
❏ surgical
• seek and suture lower genital tract lacerations
• D&C (beware of vigorous scraping which may cause Asherman syndrome)
• hypogastric, ovarian artery or uterine artery ligation
• arterial embolization
• hysterectomy (last option)
Complications
❏ Sheehan syndrome (pituitary necrosis)
POSTPARTUM MOOD ALTERATIONS
Postpartum blues
❏ very common, 85% of new mothers
❏ onset day 3-10
❏ considered an extension of the “normal” hormonal changes and adjustment to a new baby
❏ self-limited, does not last more than 2 weeks
Postpartum Depression
❏ signs and symptoms of major depression occurring in a woman within
6 months of childbirth (see Psychiatry Chapter)
❏ incidence:10-20%
❏ suspect if the “blues” last beyond 2 weeks, or if the symptoms in the first two weeks are
severe (e.g. extreme disinterest in the baby, suicidal or homicidal ideation)
❏ treatment with antidepressants is often necessary
❏ interferes with bonding and attachment between mother and baby so it can have long term effects
Postpartum Psychosis
❏ rare (0.2%)
❏ presents as an acute psychotic episode, or in the context of depression
DRUGS CONTRAINDICATED IN PREGNANCY
❏ most drugs cross the placenta to some extent
❏ use any drug with caution and only if necessary
❏ Motherisk at the Hospital for Sick Children in Toronto is a valuable resource (416-813-6780)
ANTIBIOTICS
❏ safest = ampicillin, cephalosporins
❏ erythromycin
❏
❏
❏
❏
❏
• maternal liver damage (acute fatty liver)
• used only if contraindication to penicillin use
tetracyclines
• staining of child's teeth
sulpha drugs
• antifolates, therefore theoretical risk in first trimester
• risk of kernicterus in third trimester
metronidazole
• antimetabolite, therefore theoretical risk in first trimester
chloramphenicol
• grey baby syndrome (fetal circulatory collapse secondary to
accumulation since fetus cannot metabolize this drug)
fluoroquinolones
• risk of cartilage damage (in dog and rat studies)
OB44 – Obstetrics
MCCQE 2002 Review Notes
PUERPERAL COMPLICATIONS . . . CONT.
OTHER DRUGS
❏ alcohol
❏
❏
❏
❏
❏
❏
❏
❏
• increased incidence of abortion and stillbirth, congenital
anomalies, fetal alcohol syndrome (growth retardation, CNS
involvement and facial anomalies)
cigarettes
• decreased birth weight, placenta previa/abruption,
increased spontaneous abortion, preterm labour and stillbirth
anticoagulants
• fetal warfarin syndrome: nasal hypoplasia, epiphyseal stippling,
optic atrophy, mental retardation, intracranial hemorrhage
• also spontaneous abortion, stillbirth, prematurity, IUGR
ACE inhibitors
anticonvulsants
• phenytoin associated with fetal hydantoin syndrome in 5-10%:
IUGR, mental retardation, facial dysmorphogenesis, congenital anomalies
• valproate associated with NTD in 1%
• carbamazepine associated wiht NTD in 1-2%
• generally recommended that pregnant women remain on the
lowest dose anticonvulsant appropriate for their seizure type
lithium
• Ebstein's cardiac anomaly, goitre, hyponatremia
cocaine
• microcephaly, growth retardation, prematurity, MR
DES (and other estrogenic or androgenic compounds)
• vaginal adenosis, adenocarcinoma, uterine malformation in
daughters exposed to DES in utero
retinoids (e.g. Accutane)
• CNS, craniofacial, cardiovascular, and thymic anomalies
IMMUNIZATIONS
❏ administration is dependent on the risk of infection vs. risk of
immunization complications
❏ safe
• tetanus toxoid, typhoid fever (killed bacterial), diphtheria, influenza, hepatitis B
❏ avoid live vaccines (risk of placental and fetal infection)
• polio and mumps, varicella
❏ contraindicated
• rubella
BREASTFEEDING AND DRUGS
❏ safe
•
•
•
❏ avoid
•
•
•
•
•
•
•
•
penicillins, aminoglycosides, cephalosporins
oral contraceptive use (low dose) is now believed to be safe
depoprovera
chloramphenicol (bone marrow suppression)
metronidazole (mutagenic in vitro)
sulphonamides (hemolysis with G6PD deficiency)
nitrofurantoin (hemolysis with G6PD deficiency)
tetracycline (stains teeth and bones)
lithium
antineoplastics and immunosuppressants
psychotropic drugs (relative)
REFERENCES
www.acog.org
www.socg.medical.org
Baskett, T. Essential Management of Obstetric Emergencies. [3rd ed.]. Clinical Press, Bristol, 1999.
Bastian LA, Piscitelli JT. Is this patient pregnant? Can you reliably rule in or rule out early pregnancy by clinical examination?
JAMA. 1997 Aug 20;278(7):586-91. Review.
MCCQE 2002 Review Notes
Obstetrics – OB45
Illustrated by Jen Polk